diff options
| -rw-r--r-- | OvmfPkg/Library/PlatformInitLib/Platform.c | 81 |
1 files changed, 58 insertions, 23 deletions
diff --git a/OvmfPkg/Library/PlatformInitLib/Platform.c b/OvmfPkg/Library/PlatformInitLib/Platform.c index 9ab0342fd8..d1be5c2d79 100644 --- a/OvmfPkg/Library/PlatformInitLib/Platform.c +++ b/OvmfPkg/Library/PlatformInitLib/Platform.c @@ -405,6 +405,61 @@ 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;
}
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