On 2020/6/13 17:14, Xiaoyao Li wrote:
On 6/13/2020 4:09 PM, Like Xu wrote:
When the LBR feature is reported by the vmx_get_perf_capabilities(),
the LBR fields in the [vmx|vcpu]_supported debugctl should be unmasked.
The debugctl msr is handled separately in vmx/svm and they're not
completely identical, hence remove the common msr handling code.
Signed-off-by: Like Xu <like.xu@xxxxxxxxxxxxxxx>
---
arch/x86/kvm/vmx/capabilities.h | 12 ++++++++++++
arch/x86/kvm/vmx/pmu_intel.c | 19 +++++++++++++++++++
arch/x86/kvm/x86.c | 13 -------------
3 files changed, 31 insertions(+), 13 deletions(-)
diff --git a/arch/x86/kvm/vmx/capabilities.h
b/arch/x86/kvm/vmx/capabilities.h
index b633a90320ee..f6fcfabb1026 100644
--- a/arch/x86/kvm/vmx/capabilities.h
+++ b/arch/x86/kvm/vmx/capabilities.h
@@ -21,6 +21,8 @@ extern int __read_mostly pt_mode;
#define PMU_CAP_FW_WRITES (1ULL << 13)
#define PMU_CAP_LBR_FMT 0x3f
+#define DEBUGCTLMSR_LBR_MASK (DEBUGCTLMSR_LBR |
DEBUGCTLMSR_FREEZE_LBRS_ON_PMI)
+
struct nested_vmx_msrs {
/*
* We only store the "true" versions of the VMX capability MSRs. We
@@ -387,4 +389,14 @@ static inline u64 vmx_get_perf_capabilities(void)
return perf_cap;
}
+static inline u64 vmx_get_supported_debugctl(void)
+{
+ u64 val = 0;
+
+ if (vmx_get_perf_capabilities() & PMU_CAP_LBR_FMT)
+ val |= DEBUGCTLMSR_LBR_MASK;
+
+ return val;
+}
+
#endif /* __KVM_X86_VMX_CAPS_H */
diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c
index a953c7d633f6..d92e95b64c74 100644
--- a/arch/x86/kvm/vmx/pmu_intel.c
+++ b/arch/x86/kvm/vmx/pmu_intel.c
@@ -187,6 +187,7 @@ static bool intel_is_valid_msr(struct kvm_vcpu
*vcpu, u32 msr)
case MSR_CORE_PERF_GLOBAL_OVF_CTRL:
ret = pmu->version > 1;
break;
+ case MSR_IA32_DEBUGCTLMSR:
case MSR_IA32_PERF_CAPABILITIES:
ret = 1;
break;
@@ -237,6 +238,9 @@ static int intel_pmu_get_msr(struct kvm_vcpu *vcpu,
struct msr_data *msr_info)
return 1;
msr_info->data = vcpu->arch.perf_capabilities;
return 0;
+ case MSR_IA32_DEBUGCTLMSR:
+ msr_info->data = vmcs_read64(GUEST_IA32_DEBUGCTL);
Can we put the emulation of MSR_IA32_DEBUGCTLMSR in vmx_{get/set})_msr().
AFAIK, MSR_IA32_DEBUGCTLMSR is not a pure PMU related MSR that there is
bit 2 to enable #DB for bus lock.
We already have "case MSR_IA32_DEBUGCTLMSR" handler in the vmx_set_msr()
and you may apply you bus lock changes in that handler.
+ return 0;
default:
if ((pmc = get_gp_pmc(pmu, msr, MSR_IA32_PERFCTR0)) ||
(pmc = get_gp_pmc(pmu, msr, MSR_IA32_PMC0))) {
@@ -282,6 +286,16 @@ static inline bool lbr_is_compatible(struct
kvm_vcpu *vcpu)
return true;
}
+static inline u64 vcpu_get_supported_debugctl(struct kvm_vcpu *vcpu)
+{
+ u64 debugctlmsr = vmx_get_supported_debugctl();
+
+ if (!lbr_is_enabled(vcpu))
+ debugctlmsr &= ~DEBUGCTLMSR_LBR_MASK;
+
+ return debugctlmsr;
+}
+
static int intel_pmu_set_msr(struct kvm_vcpu *vcpu, struct msr_data
*msr_info)
{
struct kvm_pmu *pmu = vcpu_to_pmu(vcpu);
@@ -336,6 +350,11 @@ static int intel_pmu_set_msr(struct kvm_vcpu *vcpu,
struct msr_data *msr_info)
}
vcpu->arch.perf_capabilities = data;
return 0;
+ case MSR_IA32_DEBUGCTLMSR:
+ if (data & ~vcpu_get_supported_debugctl(vcpu))
+ return 1;
+ vmcs_write64(GUEST_IA32_DEBUGCTL, data);
+ return 0;
default:
if ((pmc = get_gp_pmc(pmu, msr, MSR_IA32_PERFCTR0)) ||
(pmc = get_gp_pmc(pmu, msr, MSR_IA32_PMC0))) {
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 00c88c2f34e4..56f275eb4554 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2840,18 +2840,6 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu,
struct msr_data *msr_info)
return 1;
}
break;
- case MSR_IA32_DEBUGCTLMSR:
- if (!data) {
- /* We support the non-activated case already */
- break;
- } else if (data & ~(DEBUGCTLMSR_LBR | DEBUGCTLMSR_BTF)) {
So after this patch, guest trying to set bit DEBUGCTLMSR_BTF will get a
#GP instead of being ignored and printing a log in kernel.
Since the BTF is not implemented on the KVM at all,
I do propose not left this kind of dummy thing in the future KVM code.
Let's see if Netware or any BTF user will complain about this change.
These codes were introduced ~12 years ago in commit b5e2fec0ebc3 ("KVM:
Ignore DEBUGCTL MSRs with no effect"), just to make Netware happy. Maybe
I'm overthinking for that too old thing.
- /* Values other than LBR and BTF are vendor-specific,
- thus reserved and should throw a #GP */
- return 1;
- }
- vcpu_unimpl(vcpu, "%s: MSR_IA32_DEBUGCTLMSR 0x%llx, nop\n",
- __func__, data);
- break;
case 0x200 ... 0x2ff:
return kvm_mtrr_set_msr(vcpu, msr, data);
case MSR_IA32_APICBASE:
@@ -3120,7 +3108,6 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu,
struct msr_data *msr_info)
switch (msr_info->index) {
case MSR_IA32_PLATFORM_ID:
case MSR_IA32_EBL_CR_POWERON:
- case MSR_IA32_DEBUGCTLMSR:
case MSR_IA32_LASTBRANCHFROMIP:
case MSR_IA32_LASTBRANCHTOIP:
case MSR_IA32_LASTINTFROMIP:
