Change the image verification policy for option ROM images to 0x00
(ALWAYS_EXECUTE).
While this may not be a good idea for physical platforms (see e.g.
<https://trmm.net/Thunderstrike>), on the QEMU platform the benefits seem
to outweigh the drawbacks:
- For QEMU's virtual PCI devices, and for some assigned PCI devices, the
option ROMs come from host-side files, which can never be rewritten from
within the guest. Since the host admin has full control over a guest
anyway, executing option ROMs that originate from host-side files
presents no additional threat to the guest.
- For assigned physical PCI devices with option ROMs, the argument is not
so clear-cut. In theory a setup could exist where:
- the host-side UEFI firmware (with DENY_EXECUTE_ON_SECURITY_VIOLATION)
rejects the option ROM of a malicious physical PCI device, but
- when the device is assigned to the guest, OVMF executes the option ROM
in the guest,
- the option ROM breaks out of the guest (using an assumed QEMU
vulnerability) and gains QEMU user privileges on the host.
However, in order to escalate as far as it would happen on the bare
metal with ALWAYS_EXECUTE (i.e., in order to gain firmware-level access
on the host), the malicious option ROM would have to break through (1)
QEMU, (2) traditional UID and GID based privilege separation on the
host, (3) sVirt (SELinux) on the host, (4) the host OS - host firmware
boundary. This is not impossible, but not likely enough to discourage
the use cases below.
- This patch makes it possible to use unsigned iPXE network drivers that
QEMU presents in the option ROMs of virtual NICs and assigned SR-IOV
VFs, even if Secure Boot is in User Mode or Deployed Mode.
- The change also makes it possible to execute unsigned, outdated
(revoked), or downright malicious option ROMs of assigned physical
devices in guests, for corporate, entertainment, academia, or security
research purposes.
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Chao Zhang <chao.b.zhang@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Chao Zhang <chao.b.zhang@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19614 6f19259b-4bc3-4df7-8a09-765794883524
Secure Boot support was originally addded to OvmfPkg on 2012-Mar-09, in
SVN r13093 (git 8cee3de7e9), titled
OvmfPkg: Enable secure-boot support when SECURE_BOOT_ENABLE==TRUE
At that time the image verification policies in
SecurityPkg/SecurityPkg.dec were:
- option ROM image: 0x00 (ALWAYS_EXECUTE)
- removable media image: 0x05 (QUERY_USER_ON_SECURITY_VIOLATION)
- fixed media image: 0x05 (QUERY_USER_ON_SECURITY_VIOLATION)
The author of SVN r13093 apparently didn't want to depend on the
SecurityPkg defaults for the latter two image origins, plus the
ALWAYS_EXECUTE policy for option ROM images must have been deemed too lax.
For this reason SVN r13093 immediately spelled out 0x05
(QUERY_USER_ON_SECURITY_VIOLATION) within OvmfPkg for all three image
origins.
Fast forward to 2013-Aug-28: policy 0x05
(QUERY_USER_ON_SECURITY_VIOLATION) had been forbidden in the UEFI spec,
and SVN r14607 (git db44ea6c4e) reflected this in the source code:
- The policies for the latter two image origins were switched from 0x05 to
0x04 (DENY_EXECUTE_ON_SECURITY_VIOLATION) in SecurityPkg,
- the patch changed the default policy for option ROM images too, from
0x00 (ALWAYS_EXECUTE) to 0x04 (DENY_EXECUTE_ON_SECURITY_VIOLATION),
- any other client DSC files, including OvmfPkg's, underwent a whole-sale
0x05 (QUERY_USER_ON_SECURITY_VIOLATION) -> 0x04
(DENY_EXECUTE_ON_SECURITY_VIOLATION) replacement too.
The practical result of that patch for OvmfPkg was that the explicit 0x04
settings would equal the strict SecurityPkg defaults exactly.
And that's what we have today: the "override the default values from
SecurityPkg" comments in OvmfPkg's DSC files are stale, in practice.
It is extremely unlikely that SecurityPkg would change the defaults from
0x04 (DENY_EXECUTE_ON_SECURITY_VIOLATION) any time in the future, so let's
just inherit those in OvmfPkg.
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Fu Siyuan <siyuan.fu@intel.com>
Cc: Chao Zhang <chao.b.zhang@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Fu Siyuan <siyuan.fu@intel.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Chao Zhang <chao.b.zhang@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19613 6f19259b-4bc3-4df7-8a09-765794883524
GCC_ASM_EXPORT() not only exports a symbol as a function, it also emits
a .type <xxx>, %function directive, which is used by the ARM linker to
decide whether to emit interworking branches. So replace the explicit
.global with GCC_ASM_EXPORT(), or the code will not be callable from
Thumb-2 code.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Jordan Justen <jordan.l.justen@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19329 6f19259b-4bc3-4df7-8a09-765794883524
warning C4459: declaration of 'xs' hides global declaration.
Update code to rename local variable xs to xsp to be different.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Liming Gao <liming.gao@intel.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
Acked-by: Michael Kinney <michael.d.kinney@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19116 6f19259b-4bc3-4df7-8a09-765794883524
At the moment, the "UefiCpuPkg/Universal/Acpi/S3Resume2Pei" module doesn't
support S3 resume if the platform has SMM enabled and the PEI phase is
built for X64. We document this in the README, but it is not conspicuous
enough.
Replace the "fine print" in the README with a runtime check in
PlatformPei.
Cc: Jordan Justen <jordan.l.justen@intel.com>
Suggested-by: Jordan Justen <jordan.l.justen@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19070 6f19259b-4bc3-4df7-8a09-765794883524
When -D SMM_REQUIRE is given, replace both
- OvmfPkg/QemuFlashFvbServicesRuntimeDxe/FvbServicesRuntimeDxe.inf and
- OvmfPkg/EmuVariableFvbRuntimeDxe/Fvb.inf
with
- OvmfPkg/QemuFlashFvbServicesRuntimeDxe/FvbServicesSmm.inf.
The outermost (= runtime DXE driver) VariableSmmRuntimeDxe enters SMM, and
the rest:
- the privileged half of the variable driver, VariableSmm,
- the fault tolerant write driver, FaultTolerantWriteSmm,
- and the FVB driver, FvbServicesSmm,
work in SMM purely.
We also resolve the BaseCryptLib class for DXE_SMM_DRIVER modules, for the
authenticated VariableSmm driver's sake.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19065 6f19259b-4bc3-4df7-8a09-765794883524
The following modules constitute the variable driver stack:
- QemuFlashFvbServicesRuntimeDxe and EmuVariableFvbRuntimeDxe, runtime
alternatives for providing the Firmware Volume Block(2) Protocol,
dependent on qemu pflash presence,
- FaultTolerantWriteDxe, providing the Fault Tolerant Write Protocol,
- MdeModulePkg/Universal/Variable/RuntimeDxe, independently of
-D SECURE_BOOT_ENABLE, providing the Variable and Variable Write
Architectural Protocols.
Let's move these drivers closer to each other in the DSC and FDF files, so
that we can switch the variable driver stack to SMM with more local
changes.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19064 6f19259b-4bc3-4df7-8a09-765794883524
When the user requires "security" by passing -D SMM_REQUIRE, and
consequently by setting PcdSmmSmramRequire, enforce flash-based variables.
Furthermore, add two ASSERT()s to catch if the wrong module were pulled
into the build.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19063 6f19259b-4bc3-4df7-8a09-765794883524
At this point we can enable building PiSmmCpuDxeSmm.
CPU specific features, like SMRR detection, and functions that are used to
initialize SMM and process SMIs, are abstracted through the
SmmCpuFeaturesLib class for the PiSmmCpuDxeSmm module. Resolve it to our
own implementation under OvmfPkg -- it allows PiSmmCpuDxeSmm to work with
QEMU's and KVM's 64-bit state save map format, which follows the
definition from AMD's programmer manual.
SmmCpuPlatformHookLib provides platform specific functions that are used
to initialize SMM and process SMIs. Resolve it to the one Null instance
provided by UefiCpuPkg, which is expected to work for most platforms.
Cc: Paolo Bonzini <pbonzini@redhat.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
[pbonzini@redhat.com: resolve the SmmCpuFeaturesLib class to OVMF's own
instance]
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Michael Kinney <michael.d.kinney@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19061 6f19259b-4bc3-4df7-8a09-765794883524
The PiSmmCpuDxeSmm driver from UefiCpuPkg depends on the ACPI_CPU_DATA
structure -- created by a platform- and CPU-specific driver -- in order to
support ACPI S3. The address of this structure is communicated through the
dynamic PCD PcdCpuS3DataAddress.
The "UefiCpuPkg/Include/AcpiCpuData.h" header file documents the fields of
this structure in detail.
The simple/generic "UefiCpuPkg/CpuS3DataDxe" driver creates and populates
the structure in a conformant way, and it co-operates well with
PiSmmCpuDxeSmm, for OVMF's purposes.
PlatformBdsLib CpuS3DataDxe PiSmmCpuDxeSmm S3Resume2Pei
(DXE_DRIVER) (DXE_DRIVER) (DXE_SMM_DRIVER) (PEIM)
-------------- --------------- ---------------- --------------
normal collects data
boot except MTRR
settings into
ACPI_CPU_DATA
sets
PcdCpuS3Da...
signals
End-of-Dxe
|
+----------> collects MTRR
settings into
ACPI_CPU_DATA
installs
[Dxe]Smm
ReadyToLock
|
+---------------------------> fetches
PcdCpuS3Dat...
copies
ACPI_CPU_DATA
into SMRAM
runtime
S3
suspend
S3 transfers
resume control to
PiSmmCpuDxe...
|
uses <----+
ACPI_CPU_DATA
from SMRAM
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Michael Kinney <michael.d.kinney@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Michael Kinney <michael.d.kinney@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19060 6f19259b-4bc3-4df7-8a09-765794883524
This patch complements the previous one, "OvmfPkg: use relaxed AP SMM
synchronization mode". While that patch focuses on the case when the SMI
is raised synchronously by the BSP, on the BSP:
BSPHandler() [UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c]
SmmWaitForApArrival() [UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c]
IsSyncTimerTimeout() [UefiCpuPkg/PiSmmCpuDxeSmm/SyncTimer.c]
this patch concerns itself with the case when it is one of the APs that
raises (and sees delivered) the synchronous SMI:
APHandler() [UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c]
IsSyncTimerTimeout() [UefiCpuPkg/PiSmmCpuDxeSmm/SyncTimer.c]
Namely, in APHandler() the AP waits for the BSP to enter SMM regardless of
PcdCpuSmmSyncMode, for PcdCpuSmmApSyncTimeout microseconds (the default
value is 1 second). If the BSP doesn't show up in SMM within that
interval, then the AP brings it in with a directed SMI, and waits for the
BSP again for PcdCpuSmmApSyncTimeout microseconds.
Although during boot services, SmmControl2DxeTrigger() is only called by
the BSP, at runtime the OS can invoke runtime services from an AP (it can
even be forced with "taskset -c 1 efibootmgr"). Because on QEMU
SmmControl2DxeTrigger() only raises the SMI for the calling processor (BSP
and AP alike), the first interval above times out invariably in such cases
-- the BSP never shows up before the AP calls it in.
In order to mitigate the performance penalty, decrease
PcdCpuSmmApSyncTimeout to one tenth of its default value: 100 ms. (For
comparison, Vlv2TbltDevicePkg sets 1 ms.)
NOTE: once QEMU becomes capable of synchronous broadcast SMIs, this patch
and the previous one ("OvmfPkg: use relaxed AP SMM synchronization mode")
should be reverted, and SmmControl2DxeTrigger() should be adjusted
instead.
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Michael Kinney <michael.d.kinney@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Michael Kinney <michael.d.kinney@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19059 6f19259b-4bc3-4df7-8a09-765794883524
Port 0xb2 on QEMU only sends an SMI to the currently executing processor.
The SMI handler, however, and in particular SmmWaitForApArrival, currently
expects that SmmControl2DxeTrigger triggers an SMI IPI on all processors
rather than just the BSP. Thus all SMM invocations loop for a second (the
default value of PcdCpuSmmApSyncTimeout) before SmmWaitForApArrival sends
another SMI IPI to the APs.
With the default SmmCpuFeaturesLib, 32-bit machines must broadcast SMIs
because 32-bit machines must reset the MTRRs on each entry to system
management modes (they have no SMRRs). However, our virtual platform
does not have problems with cacheability of SMRAM, so we can use "directed"
SMIs instead. To do this, just set gUefiCpuPkgTokenSpaceGuid.PcdCpuSmmSyncMode
to 1 (aka SmmCpuSyncModeRelaxedAp). This fixes SMM on multiprocessor virtual
machines.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Michael Kinney <michael.d.kinney@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19058 6f19259b-4bc3-4df7-8a09-765794883524
This adjusts the previously introduced state save map access functions, to
account for QEMU and KVM's 64-bit state save map following the AMD spec
rather than the Intel one.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
[lersek@redhat.com: reflow commit message, convert patch to CRLF]
Cc: Paolo Bonzini <pbonzini@redhat.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Michael Kinney <michael.d.kinney@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19057 6f19259b-4bc3-4df7-8a09-765794883524
This implementation copies SMRAM state save map access from the
PiSmmCpuDxeSmm module.
The most notable change is:
- dropping support for EFI_SMM_SAVE_STATE_REGISTER_IO
- changing the implementation of EFI_SMM_SAVE_STATE_REGISTER_LMA to use
the SMM revision id instead of a local variable (which
UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.c initializes from CPUID's LM
bit). This accounts for QEMU's implementation of x86_64, which always
uses revision 0x20064 even if the LM bit is zero.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
[lersek@redhat.com: reflow commit message & fix typo, convert patch to
CRLF]
Cc: Paolo Bonzini <pbonzini@redhat.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Michael Kinney <michael.d.kinney@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19056 6f19259b-4bc3-4df7-8a09-765794883524
SMRR, MTRR, and SMM Feature Control support is not needed on a virtual
platform.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Acked-by: Laszlo Ersek <lersek@redhat.com>
[lersek@redhat.com: insert space between ASSERT and (), convert to CRLF,
refresh against SVN r18958]
Cc: Paolo Bonzini <pbonzini@redhat.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Michael Kinney <michael.d.kinney@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19055 6f19259b-4bc3-4df7-8a09-765794883524
The next patches will customize the implementation, but let's start from
the common version to better show the changes.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
[lersek@redhat.com: drop UNI file, keep whitespace intact, generate new
FILE_GUID, split off DSC changes, reflow commit message, refresh against
SVN r18958]
Cc: Paolo Bonzini <pbonzini@redhat.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Michael Kinney <michael.d.kinney@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19054 6f19259b-4bc3-4df7-8a09-765794883524
Explanation from Michael Kinney:
This PCD allows a platform to provide PlatformSmmBspElection() in a
platform specific SmmCpuPlatformHookLib instance to decide which CPU
gets elected to be the BSP in each SMI.
The SmmCpuPlatformHookLibNull [instance] always returns EFI_NOT_READY
for that function, which makes the module behave the same as the PCD
being set to FALSE.
The default is TRUE, so the platform lib is always called, so a platform
developer can implement the hook function and does not have to also
change a PCD setting for the hook function to be active.
A platform that wants to eliminate the call to the hook function
[altogether] can set the PCD to FALSE.
So for OVMF, I think it makes sense to set this PCD to FALSE in the DSC
file.
Suggested-by: Michael Kinney <michael.d.kinney@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19053 6f19259b-4bc3-4df7-8a09-765794883524
Although neither LocalApicLib instance is suitable for runtime DXE drivers
(because they access the APIC at the physical address retrieved from
either MSR_IA32_APIC_BASE_ADDRESS or PcdCpuLocalApicBaseAddress), they are
suitable for SMM drivers -- SMM drivers are not influenced by the runtime
OS's virtual address map.
PiSmmCpuDxeSmm links against LocalApicLib. 64-bit Linux guests tend to
enable x2apic mode even in simple VCPU configurations (e.g., 4 sockets, 1
core/socket, 1 thread/core):
[ 0.028173] x2apic enabled
If PiSmmCpuDxeSmm was linked with the BaseXApicLib instance (i.e., with no
x2apic support), then the next runtime service call that is backed by an
SMM driver triggers the following ASSERT in BaseXApicLib (because the
latter notices that x2apic has been enabled, which it doesn't support):
ASSERT .../UefiCpuPkg/Library/BaseXApicLib/BaseXApicLib.c(263):
ApicBaseMsr.Bits.Extd == 0
It is reasonable to give all LocalApicLib client modules in OVMF the same
level of x2apic support, hence resolve LocalApicLib globally to
BaseXApicX2ApicLib. This will not be conditional on -D SMM_REQUIRE,
because BaseXApicX2ApicLib is compatible with BaseXApicLib in any
environment where the latter can be used.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19052 6f19259b-4bc3-4df7-8a09-765794883524
UefiCpuPkg/PiSmmCpuDxeSmm depends on this library (the
RegisterCpuInterruptHandler() function specifically) to set up its
specialized page fault handler (SmiPFHandler() -> DumpModuleInfoByIp()).
It doesn't hurt to resolve this library class for all DXE_SMM_DRIVER
modules.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19050 6f19259b-4bc3-4df7-8a09-765794883524
PiSmmCpuDxeSmm depends on this library class, and it's okay to resolve it
generally for all DXE_SMM_DRIVER modules.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19049 6f19259b-4bc3-4df7-8a09-765794883524
During DXE, drivers save data in the LockBox. A save operation is layered
as follows:
- The unprivileged driver wishing to store data in the LockBox links
against the "MdeModulePkg/Library/SmmLockBoxLib/SmmLockBoxDxeLib.inf"
library instance.
The library allows the unprivileged driver to format requests for the
privileged SMM LockBox driver (see below), and to parse responses.
We apply this resolution for DXE_DRIVER modules.
- The privileged SMM LockBox driver is built from
"MdeModulePkg/Universal/LockBox/SmmLockBox/SmmLockBox.inf". This driver
has module type DXE_SMM_DRIVER and can access SMRAM.
The driver delegates command parsing and response formatting to
"MdeModulePkg/Library/SmmLockBoxLib/SmmLockBoxSmmLib.inf".
Therefore we include this DXE_SMM_DRIVER in the build, and apply said
resolution specifically to it.
(Including the driver requires us to resolve a few of other library
classes for DXE_SMM_DRIVER modules.)
- In PEI, the S3 Resume PEIM (UefiCpuPkg/Universal/Acpi/S3Resume2Pei)
retrieves data from the LockBox. It is capable of searching SMRAM
itself.
We resolve LockBoxLib to
"MdeModulePkg/Library/SmmLockBoxLib/SmmLockBoxPeiLib.inf" specifically
for this one PEIM.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19048 6f19259b-4bc3-4df7-8a09-765794883524
Since our fake LockBox must not be selected with -D SMM_REQUIRE (see the
previous patch), it makes sense to set aside memory for it only if -D
SMM_REQUIRE is absent. Modify InitializeRamRegions() accordingly.
This patch completes the -D SMM_REQUIRE-related tweaking of the special
OVMF memory areas.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19047 6f19259b-4bc3-4df7-8a09-765794883524
When the user builds OVMF with -D SMM_REQUIRE, our LockBox implementation
must not be used, since it doesn't actually protect data in the LockBox
from the runtime guest OS. Add an according assert to
LockBoxLibInitialize().
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19046 6f19259b-4bc3-4df7-8a09-765794883524
In SVN r15306 (git commit d4ba06df), "OvmfPkg: S3 Resume: fake LockBox
protocol for BootScriptExecutorDxe", we installed a fake LockBox protocol
in OVMF's AcpiS3SaveDxe clone. While our other AcpiS3SaveDxe
customizations remain valid (or harmless), said change is invalid when
OVMF is built with -D SMM_REQUIRE and includes the real protocol provider,
"MdeModulePkg/Universal/LockBox/SmmLockBox/SmmLockBox.inf".
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19045 6f19259b-4bc3-4df7-8a09-765794883524
This driver provides EFI_SMM_CPU_IO2_PROTOCOL, which the SMM core depends
on in its gEfiDxeSmmReadyToLockProtocolGuid callback
(SmmReadyToLockHandler(), "MdeModulePkg/Core/PiSmmCore/PiSmmCore.c").
Approached on a higher level, this driver provides the SmmIo member of the
EFI_SMM_SYSTEM_TABLE2 (SMST).
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19044 6f19259b-4bc3-4df7-8a09-765794883524
"MdeModulePkg/Core/PiSmmCore/PiSmmIpl.inf" (a DXE_RUNTIME_DRIVER)
implements the SMM Initial Program Loader. It produces
EFI_SMM_BASE2_PROTOCOL and EFI_SMM_COMMUNICATION_PROTOCOL, relying on:
- EFI_SMM_ACCESS2_PROTOCOL
(provided by OvmfPkg/SmmAccess/SmmAccess2Dxe.inf),
- EFI_SMM_CONTROL2_PROTOCOL
(provided by OvmfPkg/SmmControl2Dxe/SmmControl2Dxe.inf).
(The SMM IPL also depends on EFI_SMM_CONFIGURATION_PROTOCOL_GUID, but this
dependency is not enforced in the entry point. A protocol notify callback
is registered instead, hence we can delay providing that protocol via the
PiSmmCpuDxeSmm driver that is (to be) imported from UefiCpuPkg/.)
The SMM IPL loads the SMM core into SMRAM and executes it from there.
Therefore we add the SMM core to the build as well.
For the SMM core, a number of library classes need to be resolved.
Furthermore, each FDF file must provide the GenFds.py BaseTools utility
with a build rule for SMM_CORE; we copy the DXE_CORE's rule.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19043 6f19259b-4bc3-4df7-8a09-765794883524
The EFI_SMM_COMMUNICATION_PROTOCOL implementation that is provided by the
SMM core depends on EFI_SMM_CONTROL2_PROTOCOL; see the
mSmmControl2->Trigger() call in the SmmCommunicationCommunicate() function
[MdeModulePkg/Core/PiSmmCore/PiSmmIpl.c].
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Michael Kinney <michael.d.kinney@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19042 6f19259b-4bc3-4df7-8a09-765794883524
The SMM core depends on EFI_SMM_ACCESS2_PROTOCOL. This small driver (which
is a thin wrapper around "OvmfPkg/SmmAccess/SmramInternal.c" that was
added in the previous patch) provides that protocol.
Notably, EFI_SMM_ACCESS2_PROTOCOL is for boot time only, therefore
our MODULE_TYPE is not DXE_RUNTIME_DRIVER.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Michael Kinney <michael.d.kinney@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19041 6f19259b-4bc3-4df7-8a09-765794883524
"MdeModulePkg/Library/SmmLockBoxLib/SmmLockBoxPeiLib.inf" is the
LockBoxLib instance with SMRAM access for the PEI phase.
Said library instance must, and can, access the LockBox data in SMRAM
directly if it is invoked before SMBASE relocation / SMI handler
installation. In that case, it only needs PEI_SMM_ACCESS_PPI from the
platform, and it doesn't depend on EFI_PEI_SMM_COMMUNICATION_PPI.
OVMF satisfies the description in SVN r18823 ("MdeModulePkg:
SmmLockBoxPeiLib: work without EFI_PEI_SMM_COMMUNICATION_PPI"): in OVMF,
only S3Resume2Pei links against SmmLockBoxPeiLib.
Therefore, introduce a PEIM that produces the PEI_SMM_ACCESS_PPI
interface, enabling SmmLockBoxPeiLib to work; we can omit including
"UefiCpuPkg/PiSmmCommunication/PiSmmCommunicationPei.inf".
The load / installation order of S3Resume2Pei and SmmAccessPei is
indifferent. SmmAccessPei produces the gEfiAcpiVariableGuid HOB during its
installation (which happens during PEI), but S3Resume2Pei accesses the HOB
only when the DXE IPL calls its S3RestoreConfig2 PPI member, as last act
of PEI.
MCH_SMRAM_D_LCK and MCH_ESMRAMC_T_EN are masked out the way they are, in
SmmAccessPeiEntryPoint() and SmramAccessOpen() respectively, in order to
prevent VS20xx from warning about the (otherwise fully intentional)
truncation in the UINT8 casts. (Warnings reported by Michael Kinney.)
Cc: Michael Kinney <michael.d.kinney@intel.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Michael Kinney <michael.d.kinney@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19040 6f19259b-4bc3-4df7-8a09-765794883524
PlatformPei calls GetSystemMemorySizeBelow4gb() in three locations:
- PublishPeiMemory(): on normal boot, the permanent PEI RAM is installed
so that it ends with the RAM below 4GB,
- QemuInitializeRam(): on normal boot, memory resource descriptor HOBs are
created for the RAM below 4GB; plus MTRR attributes are set
(independently of S3 vs. normal boot)
- MemMapInitialization(): an MMIO resource descriptor HOB is created for
PCI resource allocation, on normal boot, starting at max(RAM below 4GB,
2GB).
The first two of these is adjusted for the configured TSEG size, if
PcdSmmSmramRequire is set:
- In PublishPeiMemory(), the permanent PEI RAM is kept under TSEG.
- In QemuInitializeRam(), we must keep the DXE out of TSEG.
One idea would be to simply trim the [1MB .. LowerMemorySize] memory
resource descriptor HOB, leaving a hole for TSEG in the memory space
map.
The SMM IPL will however want to massage the caching attributes of the
SMRAM range that it loads the SMM core into, with
gDS->SetMemorySpaceAttributes(), and that won't work on a hole. So,
instead of trimming this range, split the TSEG area off, and report it
as a cacheable reserved memory resource.
Finally, since reserved memory can be allocated too, pre-allocate TSEG
in InitializeRamRegions(), after QemuInitializeRam() returns. (Note that
this step alone does not suffice without the resource descriptor HOB
trickery: if we omit that, then the DXE IPL PEIM fails to load and start
the DXE core.)
- In MemMapInitialization(), the start of the PCI MMIO range is not
affected.
We choose the largest option (8MB) for the default TSEG size. Michael
Kinney pointed out that the SMBASE relocation in PiSmmCpuDxeSmm consumes
SMRAM proportionally to the number of CPUs. From the three options
available, he reported that 8MB was both necessary and sufficient for the
SMBASE relocation to succeed with 255 CPUs:
- http://thread.gmane.org/gmane.comp.bios.edk2.devel/3020/focus=3137
- http://thread.gmane.org/gmane.comp.bios.edk2.devel/3020/focus=3177
Cc: Michael Kinney <michael.d.kinney@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Michael Kinney <michael.d.kinney@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19039 6f19259b-4bc3-4df7-8a09-765794883524
AddReservedMemoryBaseSizeHob() should be able to set the same resource
attributes for reserved memory as AddMemoryBaseSizeHob() sets for system
memory. Add a new parameter called "Cacheable" to
AddReservedMemoryBaseSizeHob(), and set it to FALSE in the only caller we
have at the moment.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19038 6f19259b-4bc3-4df7-8a09-765794883524
If OVMF was built with -D SMM_REQUIRE, that implies that the runtime OS is
not trusted and we should defend against it tampering with the firmware's
data.
One such datum is the PEI firmware volume (PEIFV). Normally PEIFV is
decompressed on the first boot by SEC, then the OS preserves it across S3
suspend-resume cycles; at S3 resume SEC just reuses the originally
decompressed PEIFV.
However, if we don't trust the OS, then SEC must decompress PEIFV from the
pristine flash every time, lest we execute OS-injected code or work with
OS-injected data.
Due to how FVMAIN_COMPACT is organized, we can't decompress just PEIFV;
the decompression brings DXEFV with itself, plus it uses a temporary
output buffer and a scratch buffer too, which even reach above the end of
the finally installed DXEFV. For this reason we must keep away a
non-malicious OS from DXEFV too, plus the memory up to
PcdOvmfDecomprScratchEnd.
The delay introduced by the LZMA decompression on S3 resume is negligible.
If -D SMM_REQUIRE is not specified, then PcdSmmSmramRequire remains FALSE
(from the DEC file), and then this patch has no effect (not counting some
changed debug messages).
If QEMU doesn't support S3 (or the user disabled it on the QEMU command
line), then this patch has no effect also.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19037 6f19259b-4bc3-4df7-8a09-765794883524
The DecompressMemFvs() function in "OvmfPkg/Sec/SecMain.c" uses more
memory, temporarily, than what PEIFV and DXEFV will ultimately need.
First, it uses an output buffer for decompression, second, the
decompression itself needs a scratch buffer (and this scratch buffer is
the highest area that SEC uses).
DecompressMemFvs() used to be called on normal boots only (ie. not on S3
resume), which is why the decompression output buffer and the scratch
buffer were allowed to scribble over RAM. However, we'll soon start to
worry during S3 resume that the runtime OS might tamper with the
pre-decompressed PEIFV, and we'll decompress the firmware volumes on S3
resume too, from pristine flash. For this we'll need to know the end of
the scratch buffer in advance, so we can prepare a non-malicious OS for
it.
Calculate the end of the scratch buffer statically in the FDF files, and
assert in DecompressMemFvs() that the runtime decompression will match it.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19036 6f19259b-4bc3-4df7-8a09-765794883524
BaseExtractGuidedSectionLib uses a table at the static physical address
PcdGuidedExtractHandlerTableAddress, and modules that are linked against
BaseExtractGuidedSectionLib are expected to work together on that table.
Namely, some modules can register handlers for GUIDed sections, some other
modules can decode such sections with the pre-registered handlers. The
table carries persistent information between these modules.
BaseExtractGuidedSectionLib checks a table signature whenever it is used
(by whichever module that is linked against it), and at the first use
(identified by a signature mismatch) it initializes the table.
One of the module types that BaseExtractGuidedSectionLib can be used with
is SEC, if the SEC module in question runs with the platform's RAM already
available.
In such cases the question emerges whether the initial contents of the RAM
(ie. contents that predate the very first signature check) can be trusted.
Normally RAM starts out with all zeroes (leading to a signature mismatch
on the first check); however a malicious runtime OS can populate the area
with some payload, then force a warm platform reset or an S3
suspend-and-resume. In such cases the signature check in the SEC module
might not fire, and ExtractGuidedSectionDecode() might run code injected
by the runtime OS, as part of SEC (ie. with high privileges).
Therefore we clear the handler table in SEC.
See also git commit ad43bc6b2e (SVN rev 15433) -- this patch secures the
(d) and (e) code paths examined in that commit. Furthermore, a
non-malicious runtime OS will observe no change in behavior; see case (c)
in said commit.
Cc: Michael Kinney <michael.d.kinney@intel.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
[michael.d.kinney@intel.com: prevent VS20xx loop intrinsic with volatile]
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Michael Kinney <michael.d.kinney@intel.com>
Reviewed-by: Michael Kinney <michael.d.kinney@intel.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19035 6f19259b-4bc3-4df7-8a09-765794883524
This build time flag and corresponding Feature PCD will control whether
OVMF supports (and, equivalently, requires) SMM/SMRAM support from QEMU.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19034 6f19259b-4bc3-4df7-8a09-765794883524
Before introducing the SMM driver interface, clean up #include directives
and [LibraryClasses] by:
- removing what's not directly used (HobLib and UefiLib),
- adding what's used but not spelled out (DevicePathLib),
- sorting the result.
This helps with seeing each source file's dependencies and with
determining the library classes for the SMM driver.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18672 6f19259b-4bc3-4df7-8a09-765794883524
In preparation for introducing an SMM interface to this driver, move the
following traits to separate files, so that we can replace them in the new
SMM INF file:
- Protocol installations. The SMM driver will install protocol interfaces
in the SMM protocol database, using SMM services.
- Virtual address change handler and pointer conversions. SMM drivers run
with physical mappings and pointers must not be converted.
There are further restrictions and changes for an SMM driver, but the rest
of the code either complies with those already, or will handle the changes
transparently. For example:
- SMM drivers have access to both UEFI and SMM protocols in their entry
points (see the PI spec 1.4, "1.7 SMM Driver Initialization"),
- MemoryAllocationLib has an SMM instance that serves allocation requests
with the gSmst->SmmAllocatePool() service transparently, allocating
runtime-marked SMRAM.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18671 6f19259b-4bc3-4df7-8a09-765794883524
Currently the EFI_FW_VOL_INSTANCE and ESAL_FWB_GLOBAL structures declare
the following entries as arrays, with two entries each:
- EFI_FW_VOL_INSTANCE.FvBase[2]
- ESAL_FWB_GLOBAL.FvInstance[2]
In every case, the entry at subscript zero is meant as "physical address",
while the entry at subscript one is meant as "virtual address" -- a
pointer to the same object. The virtual address entry is originally
initialized to the physical address, and then it is converted to the
virtual mapping in FvbVirtualddressChangeEvent().
Functions that (a) read the listed fields and (b) run both before and
after the virtual address change event -- since this is a runtime DXE
driver -- derive the correct array subscript by calling the
EfiGoneVirtual() function from UefiRuntimeLib.
The problem with the above infrastructure is that it's entirely
superfluous.
EfiGoneVirtual() "knows" whether EFI has gone virtual only because the
UefiRuntimeLib constructor registers the exact same kind of virtual
address change callback, and the callback flips a static variabe to TRUE,
and EfiGoneVirtual() queries that static variable.
In effect this means for QemuFlashFvbServicesRuntimeDxe: "when there is a
virtual address change, convert the entries with subscript one from
physical to virtual, and from then on use the entries with subscript one".
This would only make sense if QemuFlashFvbServicesRuntimeDxe ever needed
the original (physical) addresses (ie. the entries with subscript zero)
after the virtual address change, but that is not the case.
Replace the arrays with single elements. The subscript zero elements
simply disappear, and the single elements take the role of the prior
subscript one elements.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18670 6f19259b-4bc3-4df7-8a09-765794883524
The ESAL_FWB_GLOBAL.FvbScratchSpace array is never initialized (it
contains garbage from AllocateRuntimePool()). Its element at subscript one
(=FVB_VIRTUAL), containing garbage as well, is converted to virtual
mapping. Then the array is never used again.
Remove it.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18669 6f19259b-4bc3-4df7-8a09-765794883524
The EFI_FW_VOL_INSTANCE.FvbDevLock member is initialized and then never
used. Remove it.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18668 6f19259b-4bc3-4df7-8a09-765794883524
We build this driver for X64 as well -- the comment isn't overly
important, but it shouldn't be misleading.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18667 6f19259b-4bc3-4df7-8a09-765794883524
Some of the line lengths in this driver are atrocious. While we have to
put up with the status quo outside of OvmfPkg, we can at least rewrap this
driver before refactoring it.
In the FvbInitialize() function there's no way around introducing two
local variables, just for the sake of sensibly rewrapping the code.
Furthermore, in "FwBlockService.c" the function comment blocks are now
indented; their original position causes diff to print bogus function
names at the top of hunks.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18666 6f19259b-4bc3-4df7-8a09-765794883524
Empty cdroms are not going to connect, avoid waiting for the backend to
switch to state 4, which is never going to happen, and return
error instead from XenPvBlockFrontInitialization(). Detect an
empty cdrom by looking at the "params" node on xenstore, which is set to
"" or "aio:" for empty drives by libxl.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18651 6f19259b-4bc3-4df7-8a09-765794883524
(1) VirtioLib allocates the virtio ring in EfiBootServicesData memory.
(This is intentional.) Code that executes after ExitBootServices() is
permitted to reuse such memory.
(2) The hypervisor is allowed to look at, and act upon, a live virtio ring
at any time, even without explicit virtio kicks from the guest.
Should boot loader code or kernel code, running between ExitBootServices()
and the kernel's own virtio drivers resetting the device, overwrite the
pages that used to contain the virtio ring before ExitBootServices(), QEMU
could theoretically interpret that unrelated data as garbage ring
contents, and abort the guest.
Although we have seen no such reports, better be prudent and reset the
device in an ExitBootServices() event handler. Among other things, this
causes QEMU to forget about the device's virtio ring.
Cc: Jordan Justen <jordan.l.justen@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18624 6f19259b-4bc3-4df7-8a09-765794883524
Jordan Justen
Laszlo Ersek
Ard Biesheuvel
Liming Gao
Paolo Bonzini
Michael Kinney
Star Zeng
Stefano Stabellini