Use an explicit case statement to grab the full range of MCx bank MSRs
in {g,s}et_msr_mce(), and manually check only the "end" (the number of
banks configured by userspace may be less than the max). The "default"
trick works, but is a bit odd now, and will be quite odd if/when support
for accessing MCx_CTL2 MSRs is added, which has near identical logic.
Hoist "offset" to function scope so as to avoid curly braces for the case
statement, and because MCx_CTL2 support will need the same variables.
Opportunstically clean up the comment about allowing bit 10 to be cleared
from bank 4.
No functional change intended.
Cc: Jue Wang <juew@xxxxxxxxxx>
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
arch/x86/kvm/x86.c | 71 ++++++++++++++++++++++++----------------------
1 file changed, 37 insertions(+), 34 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index bc6db58975dc..7e685ea9882b 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3206,6 +3206,7 @@ static int set_msr_mce(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
unsigned bank_num = mcg_cap & 0xff;
u32 msr = msr_info->index;
u64 data = msr_info->data;
+ u32 offset, last_msr;
switch (msr) {
case MSR_IA32_MCG_STATUS:
@@ -3219,32 +3220,33 @@ static int set_msr_mce(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
return 1;
vcpu->arch.mcg_ctl = data;
break;
+ case MSR_IA32_MC0_CTL ... MSR_IA32_MCx_CTL(KVM_MAX_MCE_BANKS) - 1:
+ last_msr = MSR_IA32_MCx_CTL(bank_num) - 1;
+ if (msr > last_msr)
+ return 1;
+
+ offset = array_index_nospec(msr - MSR_IA32_MC0_CTL,
+ last_msr + 1 - MSR_IA32_MC0_CTL);
+
+ /*
+ * Only 0 or all 1s can be written to IA32_MCi_CTL, all other
+ * values are architecturally undefined. But, some Linux
+ * kernels clear bit 10 in bank 4 to workaround a BIOS/GART TLB
+ * issue on AMD K8s, allow bit 10 to be clear when setting all
+ * other bits in order to avoid an uncaught #GP in the guest.
+ */
+ if ((offset & 0x3) == 0 &&
+ data != 0 && (data | (1 << 10)) != ~(u64)0)
+ return 1;
+
+ /* MCi_STATUS */
+ if (!msr_info->host_initiated && (offset & 0x3) == 1 &&
+ data != 0 && !can_set_mci_status(vcpu))
+ return 1;
+
+ vcpu->arch.mce_banks[offset] = data;
+ break;
default:
- if (msr >= MSR_IA32_MC0_CTL &&
- msr < MSR_IA32_MCx_CTL(bank_num)) {
- u32 offset = array_index_nospec(
- msr - MSR_IA32_MC0_CTL,
- MSR_IA32_MCx_CTL(bank_num) - MSR_IA32_MC0_CTL);
-
- /* only 0 or all 1s can be written to IA32_MCi_CTL
- * some Linux kernels though clear bit 10 in bank 4 to
- * workaround a BIOS/GART TBL issue on AMD K8s, ignore
- * this to avoid an uncatched #GP in the guest
- */
- if ((offset & 0x3) == 0 &&
- data != 0 && (data | (1 << 10)) != ~(u64)0)
- return 1;
-
- /* MCi_STATUS */
- if (!msr_info->host_initiated &&
- (offset & 0x3) == 1 && data != 0) {
- if (!can_set_mci_status(vcpu))
- return 1;
- }
-
- vcpu->arch.mce_banks[offset] = data;
- break;
- }
return 1;
}
return 0;
@@ -3789,6 +3791,7 @@ static int get_msr_mce(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata, bool host)
u64 data;
u64 mcg_cap = vcpu->arch.mcg_cap;
unsigned bank_num = mcg_cap & 0xff;
+ u32 offset, last_msr;
switch (msr) {
case MSR_IA32_P5_MC_ADDR:
@@ -3806,16 +3809,16 @@ static int get_msr_mce(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata, bool host)
case MSR_IA32_MCG_STATUS:
data = vcpu->arch.mcg_status;
break;
- default:
- if (msr >= MSR_IA32_MC0_CTL &&
- msr < MSR_IA32_MCx_CTL(bank_num)) {
- u32 offset = array_index_nospec(
- msr - MSR_IA32_MC0_CTL,
- MSR_IA32_MCx_CTL(bank_num) - MSR_IA32_MC0_CTL);
+ case MSR_IA32_MC0_CTL ... MSR_IA32_MCx_CTL(KVM_MAX_MCE_BANKS) - 1:
+ last_msr = MSR_IA32_MCx_CTL(bank_num) - 1;
+ if (msr > last_msr)
+ return 1;
- data = vcpu->arch.mce_banks[offset];
- break;
- }
+ offset = array_index_nospec(msr - MSR_IA32_MC0_CTL,
+ last_msr + 1 - MSR_IA32_MC0_CTL);
+ data = vcpu->arch.mce_banks[offset];
+ break;
+ default:
return 1;
}
*pdata = data;
--
2.36.0.550.gb090851708-goog
