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OvmfPkg/PlatformInitLib: factor out PlatformCpuCountBugCheck() 

Move the QEMU v2.7 reset bug check/workaround to a separate function, as
we'll need to detect further issues.

Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: Erdem Aktas <erdemaktas@google.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: James Bottomley <jejb@linux.ibm.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Michael Brown <mcb30@ipxe.org>
Cc: Min Xu <min.m.xu@intel.com>
Cc: Oliver Steffen <osteffen@redhat.com>
Cc: Sebastien Boeuf <sebastien.boeuf@intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Bugzilla: https://bugzilla.tianocore.org/show_bug.cgi?id=4250
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Message-Id: <20230119110131.91923-2-lersek@redhat.com>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Hugely-appreciated-by: Michael Brown <mcb30@ipxe.org>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>
This commit is contained in:
Laszlo Ersek 2023-01-19 12:01:30 +01:00 committed by mergify[bot]
parent 3beb8c9654
commit c3e128a4cd
1 changed files with 58 additions and 23 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

81
OvmfPkg/Library/PlatformInitLib/Platform.c
View File

@ -404,6 +404,61 @@ PlatformMiscInitialization (
}
}
/**
Check for various QEMU bugs concerning CPU numbers.
Compensate for those bugs if various conditions are satisfied, by updating a
suitable subset of the input-output parameters. The function may not return
(it may hang deliberately), even in RELEASE builds, if the QEMU bug is
impossible to cover up.
@param[in,out] BootCpuCount On input, the boot CPU count reported by QEMU via
fw_cfg (QemuFwCfgItemSmpCpuCount). The caller is
responsible for ensuring (BootCpuCount > 0); that
is, if QEMU does not provide the boot CPU count
via fw_cfg *at all*, then this function must not
be called.
@param[in,out] Present On input, the number of present-at-boot CPUs, as
reported by QEMU through the modern CPU hotplug
register block.
@param[in,out] Possible On input, the number of possible CPUs, as
reported by QEMU through the modern CPU hotplug
register block.
**/
STATIC
VOID
PlatformCpuCountBugCheck (
IN OUT UINT16 *BootCpuCount,
IN OUT UINT32 *Present,
IN OUT UINT32 *Possible
)
{
ASSERT (*BootCpuCount > 0);
//
// Sanity check: fw_cfg and the modern CPU hotplug interface should expose the
// same boot CPU count.
//
if (*BootCpuCount != *Present) {
DEBUG ((
DEBUG_WARN,
"%a: QEMU v2.7 reset bug: BootCpuCount=%d Present=%u\n",
__FUNCTION__,
*BootCpuCount,
*Present
));
//
// The handling of QemuFwCfgItemSmpCpuCount, across CPU hotplug plus
// platform reset (including S3), was corrected in QEMU commit e3cadac073a9
// ("pc: fix FW_CFG_NB_CPUS to account for -device added CPUs", 2016-11-16),
// part of release v2.8.0.
//
*BootCpuCount = (UINT16)*Present;
}
}
/**
Fetch the boot CPU count and the possible CPU count from QEMU, and expose
them to UefiCpuPkg modules.
@ -518,8 +573,8 @@ PlatformMaxCpuCountInitialization (
UINT8 CpuStatus;
//
// Read the status of the currently selected CPU. This will help with a
// sanity check against "BootCpuCount".
// Read the status of the currently selected CPU. This will help with
// various CPU count sanity checks.
//
CpuStatus = IoRead8 (CpuHpBase + QEMU_CPUHP_R_CPU_STAT);
if ((CpuStatus & QEMU_CPUHP_STAT_ENABLED) != 0) {
@ -540,27 +595,7 @@ PlatformMaxCpuCountInitialization (
ASSERT (Selected == Possible || Selected == 0);
} while (Selected > 0);
//
// Sanity check: fw_cfg and the modern CPU hotplug interface should
// return the same boot CPU count.
//
if (BootCpuCount != Present) {
DEBUG ((
DEBUG_WARN,
"%a: QEMU v2.7 reset bug: BootCpuCount=%d "
"Present=%u\n",
__FUNCTION__,
BootCpuCount,
Present
));
//
// The handling of QemuFwCfgItemSmpCpuCount, across CPU hotplug plus
// platform reset (including S3), was corrected in QEMU commit
// e3cadac073a9 ("pc: fix FW_CFG_NB_CPUS to account for -device added
// CPUs", 2016-11-16), part of release v2.8.0.
//
BootCpuCount = (UINT16)Present;
}
PlatformCpuCountBugCheck (&BootCpuCount, &Present, &Possible);
MaxCpuCount = Possible;
}