The Intel erratum for "incomplete Global INVLPG flushes" says:
This erratum does not apply in VMX non-root operation. It applies
only when PCIDs are enabled and either in VMX root operation or
outside VMX operation.
So if the kernel is running in a hypervisor, we are in VMX non-root
operation and we should be safe to use PCID.
Cc: Dave Hansen <[email protected]>
Cc: Michael Kelley <[email protected]>
Cc: Pawan Gupta <[email protected]>
Cc: Sean Christopherson <[email protected]>
Cc: Andrew Cooper <[email protected]>
Link: https://lore.kernel.org/all/168436059559.404.13934972543631851306.tip-bot2@tip-bot2/
Link: https://cdrdv2.intel.com/v1/dl/getContent/740518 # RPL042, rev. 13
Link: https://cdrdv2.intel.com/v1/dl/getContent/682436 # ADL063, rev. 24
Signed-off-by: Xi Ruoyao <[email protected]>
---
arch/x86/mm/init.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
index e960196e8058..1efd55835fc5 100644
--- a/arch/x86/mm/init.c
+++ b/arch/x86/mm/init.c
@@ -279,7 +279,7 @@ static const struct x86_cpu_id invlpg_miss_ids[] = {
static void setup_pcid(void)
{
- const struct x86_cpu_id *invlpg_miss_match;
+ const struct x86_cpu_id *invlpg_miss_match = NULL;
if (!IS_ENABLED(CONFIG_X86_64))
return;
@@ -287,7 +287,9 @@ static void setup_pcid(void)
if (!boot_cpu_has(X86_FEATURE_PCID))
return;
- invlpg_miss_match = x86_match_cpu(invlpg_miss_ids);
+ /* Only bare-metal is affected. PCIDs in guests are OK. */
+ if (!boot_cpu_has(X86_FEATURE_HYPERVISOR))
+ invlpg_miss_match = x86_match_cpu(invlpg_miss_ids);
if (invlpg_miss_match &&
boot_cpu_data.microcode < invlpg_miss_match->driver_data) {
--
2.45.1