BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3008
The QemuFlashPtrWrite() flash services runtime uses the GHCB and VmgExit()
directly to perform the flash write when running as an SEV-ES guest. If an
interrupt arrives between VmgInit() and VmgExit(), the Dr7 read in the
interrupt handler will generate a #VC, which can overwrite information in
the GHCB that QemuFlashPtrWrite() has set. This has been seen with the
timer interrupt firing and the CpuExceptionHandlerLib library code,
UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/
Xcode5ExceptionHandlerAsm.nasm and
ExceptionHandlerAsm.nasm
reading the Dr7 register while QemuFlashPtrWrite() is using the GHCB. In
general, it is necessary to protect the GHCB whenever it is used, not just
in QemuFlashPtrWrite().
Disable interrupts around the usage of the GHCB by modifying the VmgInit()
and VmgDone() interfaces:
- VmgInit() will take an extra parameter that is a pointer to a BOOLEAN
that will hold the interrupt state at the time of invocation. VmgInit()
will get and save this interrupt state before updating the GHCB.
- VmgDone() will take an extra parameter that is used to indicate whether
interrupts are to be (re)enabled. Before exiting, VmgDone() will enable
interrupts if that is requested.
Fixes: 437eb3f7a8
Cc: Eric Dong <eric.dong@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Rahul Kumar <rahul1.kumar@intel.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Ard Biesheuvel <ard.biesheuvel@arm.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Acked-by: Eric Dong <eric.dong@intel.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Message-Id: <c326a4fd78253f784b42eb317589176cf7d8592a.1604685192.git.thomas.lendacky@amd.com>
BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3008
In upcoming patches, the setting of the bits in the GHCB ValidBitmap will
be performed in multiple places. In order to reduce code duplication, add
an interface, VmgSetOffsetValid(), to VmgExitLib library to perform this
function. Also, to keep management of the ValidBitmap within the library,
add an inteface, VmgIsOffsetValid(), to return whether the bit in the
ValidBitmap is set for a specified offset.
The new VmgSetOffsetValid() function is a VOID function and will be an
empty function in the VmgExitLibNull implementation of the VmgExitLib
library.
The new VmgIsOffsetValid() function returns a BOOLEAN to indicate if the
offset is valid. This will always return FALSE in the VmgExitLibNull
implementation of the VmgExitLib library.
Cc: Eric Dong <eric.dong@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Rahul Kumar <rahul1.kumar@intel.com>
Acked-by: Eric Dong <eric.dong@intel.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Message-Id: <0bcb2373f8c6e0171ae277d3d7c2eb284621355e.1604685192.git.thomas.lendacky@amd.com>
BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=2198
To support handling #VC exceptions and issuing VMGEXIT instructions,
create a library with functions that can be used to perform these
#VC/VMGEXIT related operations. This includes functions for:
- Handling #VC exceptions
- Preparing for and issuing a VMGEXIT
- Performing MMIO-related write operations to support flash emulation
- Performing AP related boot opeations
The base functions in this driver will not do anything and will return
an error if a return value is required. It is expected that other packages
(like OvmfPkg) will create a version of the library to fully support an
SEV-ES guest.
Cc: Eric Dong <eric.dong@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Eric Dong <eric.dong@intel.com>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Regression-tested-by: Laszlo Ersek <lersek@redhat.com>
Tom Lendacky