The "virsh setvcpus" (plural) command may hot-plug several VCPUs in quick
succession -- it means a series of "device_add" QEMU monitor commands,
back-to-back.
If a "device_add" occurs *just after* ACPI raises the broadcast SMI, then:
- the CPU_FOREACH() loop in QEMU's ich9_apm_ctrl_changed() cannot make the
SMI pending for the new CPU -- at that time, the new CPU doesn't even
exist yet,
- OVMF will find the new CPU however (in the CPU hotplug register block),
in QemuCpuhpCollectApicIds().
As a result, when the firmware sends an INIT-SIPI-SIPI to the new CPU in
SmbaseRelocate(), expecting it to boot into SMM (due to the pending SMI),
the new CPU instead boots straight into the post-RSM (normal mode) "pen",
skipping its initial SMI handler.
The CPU halts nicely in the pen, but its SMBASE is never relocated, and
the SMRAM message exchange with the BSP falls apart -- the BSP gets stuck
in the following loop:
//
// Wait until the hot-added CPU is just about to execute RSM.
//
while (Context->AboutToLeaveSmm == 0) {
CpuPause ();
}
because the new CPU's initial SMI handler never sets the flag to nonzero.
Fix this by sending a directed SMI to the new CPU just before sending it
the INIT-SIPI-SIPI. The various scenarios are documented in the code --
the cases affected by the patch are documented under point (2).
Note that this is not considered a security patch, as for a malicious
guest OS, the issue is not exploitable -- the symptom is a hang on the
BSP, in the above-noted loop in SmbaseRelocate(). Instead, the patch fixes
behavior for a benign guest OS.
Cc: Ard Biesheuvel <ard.biesheuvel@arm.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Philippe Mathieu-Daudé <philmd@redhat.com>
Fixes: 51a6fb4118
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=2929
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Message-Id: <20200826222129.25798-3-lersek@redhat.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@arm.com>
The "virsh setvcpus" (plural) command may hot-plug several VCPUs in quick
succession -- it means a series of "device_add" QEMU monitor commands,
back-to-back.
If a "device_add" occurs *just before* ACPI raises the broadcast SMI,
then:
- OVMF processes the hot-added CPU well.
- However, QEMU's post-SMI ACPI loop -- which clears the pending events
for the hot-added CPUs that were collected before raising the SMI -- is
unaware of the stray CPU. Thus, the pending event is not cleared for it.
As a result of the stuck event, at the next hot-plug, OVMF tries to re-add
(relocate for the 2nd time) the already-known CPU. At that time, the AP is
already in the normal edk2 SMM busy-wait however, so it doesn't respond to
the exchange that the BSP intends to do in SmbaseRelocate(). Thus the VM
gets stuck in SMM.
(Because of the above symptom, this is not considered a security patch; it
doesn't seem exploitable by a malicious guest OS.)
In CpuHotplugMmi(), skip the supposedly hot-added CPU if it's already
known. The post-SMI ACPI loop will clear the pending event for it this
time.
Cc: Ard Biesheuvel <ard.biesheuvel@arm.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Philippe Mathieu-Daudé <philmd@redhat.com>
Fixes: bc498ac4ca
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=2929
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Message-Id: <20200826222129.25798-2-lersek@redhat.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@arm.com>
With the help of the Post-SMM Pen and the SMBASE relocation functions
added in the previous patches, we can now complete the root MMI handler
for CPU hotplug.
In the driver's entry point function:
- allocate the pen (in a reserved page in normal RAM),
- install the default ("first") SMI handler for hot-added CPUs (which
includes priming the exchange area between the MM Monarch and the
hot-added CPUs, i.e., shutting the APIC ID gate).
In the root MMI handler, for each hot-added CPU:
- record the APIC ID of the new CPU in CPU_HOT_PLUG_DATA,
- relocate the SMBASE of the new CPU,
- inform PiSmmCpuDxeSmm by calling
EFI_SMM_CPU_SERVICE_PROTOCOL.AddProcessor().
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Michael Kinney <michael.d.kinney@intel.com>
Cc: Philippe Mathieu-Daudé <philmd@redhat.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=1512
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Message-Id: <20200226221156.29589-14-lersek@redhat.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Tested-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Implement the First SMI Handler for hot-added CPUs, in NASM.
Add the interfacing C-language function that the SMM Monarch calls. This
function launches and coordinates SMBASE relocation for a hot-added CPU.
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Michael Kinney <michael.d.kinney@intel.com>
Cc: Philippe Mathieu-Daudé <philmd@redhat.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=1512
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Message-Id: <20200226221156.29589-13-lersek@redhat.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Tested-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Once a hot-added CPU finishes the SMBASE relocation, we need to pen it in
a HLT loop. Add the NASM implementation (with just a handful of
instructions, but much documentation), and some C language helper
functions.
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Michael Kinney <michael.d.kinney@intel.com>
Cc: Philippe Mathieu-Daudé <philmd@redhat.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=1512
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Message-Id: <20200226221156.29589-12-lersek@redhat.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Tested-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Call QemuCpuhpCollectApicIds() in the root MMI handler. The APIC IDs of
the hotplugged CPUs will be used for several purposes in subsequent
patches.
For calling QemuCpuhpCollectApicIds(), pre-allocate both of its output
arrays "PluggedApicIds" and "ToUnplugApicIds" in the driver's entry point
function. The allocation size is dictated by the possible CPU count, which
we fetch from "CPU_HOT_PLUG_DATA.ArrayLength".
The CPU_HOT_PLUG_DATA structure in SMRAM is an out-of-band information
channel between this driver and PiSmmCpuDxeSmm, underlying
EFI_SMM_CPU_SERVICE_PROTOCOL.
In order to consume "CPU_HOT_PLUG_DATA.ArrayLength", extend the driver's
DEPEX to EFI_SMM_CPU_SERVICE_PROTOCOL. PiSmmCpuDxeSmm stores the address
of CPU_HOT_PLUG_DATA to "PcdCpuHotPlugDataAddress", before it produces
EFI_SMM_CPU_SERVICE_PROTOCOL.
Stash the protocol at once, as it will be needed later.
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Michael Kinney <michael.d.kinney@intel.com>
Cc: Philippe Mathieu-Daudé <philmd@redhat.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=1512
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Message-Id: <20200226221156.29589-11-lersek@redhat.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Tested-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Add a function that collects the APIC IDs of CPUs that have just been
hot-plugged, or are about to be hot-unplugged.
Pending events are only located and never cleared; QEMU's AML needs the
firmware to leave the status bits intact in the hotplug register block.
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Michael Kinney <michael.d.kinney@intel.com>
Cc: Philippe Mathieu-Daudé <philmd@redhat.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=1512
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Message-Id: <20200226221156.29589-10-lersek@redhat.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Philippe Mathieu-Daude <philmd@redhat.com>
Tested-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
QEMU commit 3a61c8db9d25 ("acpi: cpuhp: add CPHP_GET_CPU_ID_CMD command",
2020-01-22) introduced a new command in the modern CPU hotplug register
block that lets the firmware query the arch-specific IDs (on IA32/X64: the
APIC IDs) of CPUs. Add a macro for this command value, because we'll need
it later.
At the same time, add a sanity check for the modern hotplug interface to
CpuHotplugSmm.
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Michael Kinney <michael.d.kinney@intel.com>
Cc: Philippe Mathieu-Daudé <philmd@redhat.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=1512
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Message-Id: <20200226221156.29589-9-lersek@redhat.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Philippe Mathieu-Daude <philmd@redhat.com>
Tested-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Add a handful of simple functions for accessing QEMU's hotplug registers
more conveniently. These functions thinly wrap some of the registers
described in "docs/specs/acpi_cpu_hotplug.txt" in the QEMU tree. The
functions hang (by design) if they encounter an internal failure.
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Michael Kinney <michael.d.kinney@intel.com>
Cc: Philippe Mathieu-Daudé <philmd@redhat.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=1512
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Message-Id: <20200226221156.29589-8-lersek@redhat.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Philippe Mathieu-Daude <philmd@redhat.com>
Tested-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Add a new SMM driver skeleton that registers a root SMI handler, and
checks if the SMI control value (written to 0xB2) indicates a CPU hotplug
SMI.
QEMU's ACPI payload will cause the OS to raise a broadcast SMI when a CPU
hotplug event occurs, namely by writing value 4 to IO Port 0xB2. In other
words, control value 4 is now allocated for this purpose; introduce the
ICH9_APM_CNT_CPU_HOTPLUG macro for it.
The standard identifiers in this driver use the new MM (Management Mode)
terminology from the PI spec, not the earlier SMM (System Management Mode)
terms.
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Michael Kinney <michael.d.kinney@intel.com>
Cc: Philippe Mathieu-Daudé <philmd@redhat.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=1512
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Message-Id: <20200226221156.29589-7-lersek@redhat.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Tested-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Laszlo Ersek