On 5/6/2023 11:04 AM, Chao Gao wrote:
to avoid computing the supported value at runtime every time.
No functional change intended.
the value of kvm_get_arch_capabilities() can be changed due to
if (l1tf_vmx_mitigation != VMENTER_L1D_FLUSH_NEVER)
data |= ARCH_CAP_SKIP_VMENTRY_L1DFLUSH;
and l1tf_vmx_mitigation can be runtime changed by vmentry_l1d_flush
module param.
We need a detailed analysis that in no real case can
ARCH_CAP_SKIP_VMENTRY_L1DFLUSH bit change runtime.
Signed-off-by: Chao Gao <chao.gao@xxxxxxxxx>
---
A new call site of kvm_get_arch_capabilities() is added by [1]. It should be
replaced with the cached value in kvm_caps.
[1] https://lore.kernel.org/all/20230504181827.130532-1-mizhang@xxxxxxxxxx/
arch/x86/kvm/x86.c | 5 +++--
arch/x86/kvm/x86.h | 1 +
2 files changed, 4 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 523c39a03c00..94aa70ec169c 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1670,7 +1670,7 @@ static int kvm_get_msr_feature(struct kvm_msr_entry *msr)
{
switch (msr->index) {
case MSR_IA32_ARCH_CAPABILITIES:
- msr->data = kvm_get_arch_capabilities();
+ msr->data = kvm_caps.supported_arch_cap;
break;
case MSR_IA32_PERF_CAPABILITIES:
msr->data = kvm_caps.supported_perf_cap;
@@ -9523,6 +9523,7 @@ static int __kvm_x86_vendor_init(struct kvm_x86_init_ops *ops)
kvm_caps.max_guest_tsc_khz = max;
}
kvm_caps.default_tsc_scaling_ratio = 1ULL << kvm_caps.tsc_scaling_ratio_frac_bits;
+ kvm_caps.supported_arch_cap = kvm_get_arch_capabilities();
kvm_init_msr_lists();
return 0;
@@ -11879,7 +11880,7 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
if (r)
goto free_guest_fpu;
- vcpu->arch.arch_capabilities = kvm_get_arch_capabilities();
+ vcpu->arch.arch_capabilities = kvm_caps.supported_arch_cap;
vcpu->arch.msr_platform_info = MSR_PLATFORM_INFO_CPUID_FAULT;
kvm_xen_init_vcpu(vcpu);
kvm_vcpu_mtrr_init(vcpu);
diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index c544602d07a3..d3e524bcc169 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -29,6 +29,7 @@ struct kvm_caps {
u64 supported_xcr0;
u64 supported_xss;
u64 supported_perf_cap;
+ u64 supported_arch_cap;
};
void kvm_spurious_fault(void);
base-commit: b3c98052d46948a8d65d2778c7f306ff38366aac
