Reject attempts to set bits 63:32 for 32-bit x2APIC registers, i.e. all
x2APIC registers except ICR. Per Intel's SDM:
Non-zero writes (by WRMSR instruction) to reserved bits to these
registers will raise a general protection fault exception
Opportunistically fix a typo in a nearby comment.
Reported-by: Marc Orr <marcorr@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
arch/x86/kvm/lapic.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index f77da92c6ea6..bf53e4752f30 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -3108,13 +3108,17 @@ static int kvm_lapic_msr_read(struct kvm_lapic *apic, u32 reg, u64 *data)
static int kvm_lapic_msr_write(struct kvm_lapic *apic, u32 reg, u64 data)
{
/*
- * ICR is a 64-bit register in x2APIC mode (and Hyper'v PV vAPIC) and
+ * ICR is a 64-bit register in x2APIC mode (and Hyper-V PV vAPIC) and
* can be written as such, all other registers remain accessible only
* through 32-bit reads/writes.
*/
if (reg == APIC_ICR)
return kvm_x2apic_icr_write(apic, data);
+ /* Bits 63:32 are reserved in all other registers. */
+ if (data >> 32)
+ return 1;
+
return kvm_lapic_reg_write(apic, reg, (u32)data);
}
--
2.39.0.314.g84b9a713c41-goog
