This is doing more than exporting a function, the export isn't even the focal
point of the patch.
On Mon, Nov 08, 2021, Like Xu wrote:
> From: Like Xu <likexu@xxxxxxxxxxx>
>
> Let's export kvm_pmu_is_valid_msr() for nVMX, instead of
Please wrap at ~75 chars.
> exporting all kvm_pmu_ops for this one case.
kvm_pmu_ops doesn't exist as of this patch, it comes later in the series.
> The reduced access scope will help to optimize the kvm_x86_ops.pmu_ops stuff
> later.
The changelog needs to explain why it's ok to add the msr_idx_to_pmc() check.
Something like:
KVM: nVMX: Use kvm_pmu_is_valid_msr() to check for PERF_GLOBAL_CTRL support
Use the generic kvm_pmu_is_valid_msr() helper when determining whether or not
PERF_GLOBAL_CTRL is exposed to the guest and thus can be loaded on nested
VM-Enter/VM-Exit. The extra (indirect!) call to msr_idx_to_pmc() that comes
with the helper is unnecessary, but harmless, as it's guaranteed to return
false for MSR_CORE_PERF_GLOBAL_CTRL and this is a already a very slow path.
Using the helper will allow future code to use static_call() for the PMU ops
without having to export any static_call definitions.
Export kvm_pmu_is_valid_msr() as necessary.
All that said, looking at this whole thing again, I think I'd prefer:
>From d217914c9897d9a2cfd01073284a933ace4709b7 Mon Sep 17 00:00:00 2001
From: Sean Christopherson <seanjc@xxxxxxxxxx>
Date: Wed, 8 Dec 2021 09:48:20 -0800
Subject: [PATCH] KVM: nVMX: Refactor PMU refresh to avoid referencing
kvm_x86_ops.pmu_ops
Refactor the nested VMX PMU refresh helper to pass it a flag stating
whether or not the vCPU has PERF_GLOBAL_CTRL instead of having the nVMX
helper query the information by bouncing through kvm_x86_ops.pmu_ops.
This will allow a future patch to use static_call() for the PMU ops
without having to export any static call definitions from common x86.
Alternatively, nVMX could call kvm_pmu_is_valid_msr() to indirectly use
kvm_x86_ops.pmu_ops, but that would exporting kvm_pmu_is_valid_msr() and
incurs an extra layer of indirection.
Opportunistically rename the helper to keep line lengths somewhat
reasonable, and to better capture its high-level role.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
arch/x86/kvm/vmx/nested.c | 5 +++--
arch/x86/kvm/vmx/nested.h | 3 ++-
arch/x86/kvm/vmx/pmu_intel.c | 3 ++-
3 files changed, 7 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 08e785871985..c87a81071288 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -4773,7 +4773,8 @@ int get_vmx_mem_address(struct kvm_vcpu *vcpu, unsigned long exit_qualification,
return 0;
}
-void nested_vmx_pmu_entry_exit_ctls_update(struct kvm_vcpu *vcpu)
+void nested_vmx_pmu_refresh(struct kvm_vcpu *vcpu,
+ bool vcpu_has_perf_global_ctrl)
{
struct vcpu_vmx *vmx;
@@ -4781,7 +4782,7 @@ void nested_vmx_pmu_entry_exit_ctls_update(struct kvm_vcpu *vcpu)
return;
vmx = to_vmx(vcpu);
- if (kvm_x86_ops.pmu_ops->is_valid_msr(vcpu, MSR_CORE_PERF_GLOBAL_CTRL)) {
+ if (vcpu_has_perf_global_ctrl) {
vmx->nested.msrs.entry_ctls_high |=
VM_ENTRY_LOAD_IA32_PERF_GLOBAL_CTRL;
vmx->nested.msrs.exit_ctls_high |=
diff --git a/arch/x86/kvm/vmx/nested.h b/arch/x86/kvm/vmx/nested.h
index b69a80f43b37..c92cea0b8ccc 100644
--- a/arch/x86/kvm/vmx/nested.h
+++ b/arch/x86/kvm/vmx/nested.h
@@ -32,7 +32,8 @@ int vmx_set_vmx_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 data);
int vmx_get_vmx_msr(struct nested_vmx_msrs *msrs, u32 msr_index, u64 *pdata);
int get_vmx_mem_address(struct kvm_vcpu *vcpu, unsigned long exit_qualification,
u32 vmx_instruction_info, bool wr, int len, gva_t *ret);
-void nested_vmx_pmu_entry_exit_ctls_update(struct kvm_vcpu *vcpu);
+void nested_vmx_pmu_refresh(struct kvm_vcpu *vcpu,
+ bool vcpu_has_perf_global_ctrl);
void nested_mark_vmcs12_pages_dirty(struct kvm_vcpu *vcpu);
bool nested_vmx_check_io_bitmaps(struct kvm_vcpu *vcpu, unsigned int port,
int size);
diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c
index 1b7456b2177b..7ca870d0249d 100644
--- a/arch/x86/kvm/vmx/pmu_intel.c
+++ b/arch/x86/kvm/vmx/pmu_intel.c
@@ -529,7 +529,8 @@ static void intel_pmu_refresh(struct kvm_vcpu *vcpu)
bitmap_set(pmu->all_valid_pmc_idx,
INTEL_PMC_MAX_GENERIC, pmu->nr_arch_fixed_counters);
- nested_vmx_pmu_entry_exit_ctls_update(vcpu);
+ nested_vmx_pmu_refresh(vcpu,
+ intel_is_valid_msr(vcpu, MSR_CORE_PERF_GLOBAL_CTRL));
if (intel_pmu_lbr_is_compatible(vcpu))
x86_perf_get_lbr(&lbr_desc->records);
--
2.34.1.400.ga245620fadb-goog
