On 08/28/2019 04:41 PM, Oliver Upton wrote:
The existing implementation for loading the IA32_PERF_GLOBAL_CTRL MSR
on VM-exit was incorrect, as the next call to atomic_switch_perf_msrs()
could cause this value to be overwritten. Instead, call kvm_set_msr()
which will allow atomic_switch_perf_msrs() to correctly set the values.
Suggested-by: Jim Mattson <jmattson@xxxxxxxxxx>
Signed-off-by: Oliver Upton <oupton@xxxxxxxxxx>
---
arch/x86/kvm/vmx/nested.c | 13 ++++++++++---
1 file changed, 10 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index ced9fba32598..b0ca34bf4d21 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -3724,6 +3724,7 @@ static void load_vmcs12_host_state(struct kvm_vcpu *vcpu,
struct vmcs12 *vmcs12)
{
struct kvm_segment seg;
+ struct msr_data msr_info;
u32 entry_failure_code;
if (vmcs12->vm_exit_controls & VM_EXIT_LOAD_IA32_EFER)
@@ -3800,9 +3801,15 @@ static void load_vmcs12_host_state(struct kvm_vcpu *vcpu,
vmcs_write64(GUEST_IA32_PAT, vmcs12->host_ia32_pat);
vcpu->arch.pat = vmcs12->host_ia32_pat;
}
- if (vmcs12->vm_exit_controls & VM_EXIT_LOAD_IA32_PERF_GLOBAL_CTRL)
- vmcs_write64(GUEST_IA32_PERF_GLOBAL_CTRL,
- vmcs12->host_ia32_perf_global_ctrl);
+ if (vmcs12->vm_exit_controls & VM_EXIT_LOAD_IA32_PERF_GLOBAL_CTRL) {
+ msr_info.host_initiated = false;
+ msr_info.index = MSR_CORE_PERF_GLOBAL_CTRL;
+ msr_info.data = vmcs12->host_ia32_perf_global_ctrl;
+ if (kvm_set_msr(vcpu, &msr_info))
+ pr_debug_ratelimited(
+ "%s cannot write MSR (0x%x, 0x%llx)\n",
+ __func__, msr_info.index, msr_info.data);
+ }
/* Set L1 segment info according to Intel SDM
27.5.2 Loading Host Segment and Descriptor-Table Registers */
These patches are what I am already working on. I sent the following:
[KVM nVMX]: Check "load IA32_PERF_GLOBAL_CTRL" on vmentry of
nested guests
[PATCH 0/4][kvm-unit-test nVMX]: Test "load
IA32_PERF_GLOBAL_CONTROL" VM-entry control on vmentry of nested guests
a few months back. I got feedback from the alias and am working on v2
which I will send soon...
