[PATCH v2 34/54] KVM: x86/pmu: Switch IA32_PERF_GLOBAL_CTRL at VM boundary

Mingwei Zhang
2024-05-06T05:31:32Z

From: Xiong Zhang <xiong.y.zhang@linux.intel.com>

In PMU passthrough mode, use global_ctrl field in struct kvm_pmu as the
cached value. This is convenient for KVM to set and get the value from the
host side. In addition, load and save the value across VM enter/exit
boundary in the following way:

- At VM exit, if processor supports
GUEST_VM_EXIT_SAVE_IA32_PERF_GLOBAL_CTRL, read guest
IA32_PERF_GLOBAL_CTRL GUEST_IA32_PERF_GLOBAL_CTRL VMCS field, else read
it from VM-exit MSR-stroe array in VMCS. The value is then assigned to
global_ctrl.

- At VM Entry, if processor supports
GUEST_VM_ENTRY_LOAD_IA32_PERF_GLOBAL_CTRL, read guest
IA32_PERF_GLOBAL_CTRL from GUEST_IA32_PERF_GLOBAL_CTRL VMCS field, else
read it from VM-entry MSR-load array in VMCS. The value is then
assigned to global ctrl.

Implement the above logic into two helper functions and invoke them around
VM Enter/exit boundary.

Signed-off-by: Xiong Zhang <xiong.y.zhang@linux.intel.com>
Co-developed-by: Mingwei Zhang <mizhang@google.com>
Signed-off-by: Mingwei Zhang <mizhang@google.com>
Signed-off-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
---
arch/x86/include/asm/kvm_host.h | 2 ++
arch/x86/kvm/vmx/vmx.c | 49 ++++++++++++++++++++++++++++++++-
2 files changed, 50 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 9857dda8b851..54a56eda77f4 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -598,6 +598,8 @@ struct kvm_pmu {
u8 event_count;

bool passthrough;
+ int global_ctrl_slot_in_autoload;
+ int global_ctrl_slot_in_autostore;
};

struct kvm_pmu_ops;
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 62b5913abdd6..c86b768743a9 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -4421,6 +4421,7 @@ static void vmx_set_perf_global_ctrl(struct vcpu_vmx *vmx)
}
m->val[i].index = MSR_CORE_PERF_GLOBAL_CTRL;
m->val[i].value = 0;
+ vcpu_to_pmu(&vmx->vcpu)->global_ctrl_slot_in_autoload = i;
}
/*
* Setup auto clear host PERF_GLOBAL_CTRL msr at vm exit.
@@ -4448,6 +4449,7 @@ static void vmx_set_perf_global_ctrl(struct vcpu_vmx *vmx)
vmcs_write32(VM_EXIT_MSR_STORE_COUNT, m->nr);
}
m->val[i].index = MSR_CORE_PERF_GLOBAL_CTRL;
+ vcpu_to_pmu(&vmx->vcpu)->global_ctrl_slot_in_autostore = i;
}
} else {
if (!(vmentry_ctrl & VM_ENTRY_LOAD_IA32_PERF_GLOBAL_CTRL)) {
@@ -4458,6 +4460,7 @@ static void vmx_set_perf_global_ctrl(struct vcpu_vmx *vmx)
m->val[i] = m->val[m->nr];
vmcs_write32(VM_ENTRY_MSR_LOAD_COUNT, m->nr);
}
+ vcpu_to_pmu(&vmx->vcpu)->global_ctrl_slot_in_autoload = -ENOENT;
}
if (!(vmexit_ctrl & VM_EXIT_LOAD_IA32_PERF_GLOBAL_CTRL)) {
m = &vmx->msr_autoload.host;
@@ -4476,6 +4479,7 @@ static void vmx_set_perf_global_ctrl(struct vcpu_vmx *vmx)
m->val[i] = m->val[m->nr];
vmcs_write32(VM_EXIT_MSR_STORE_COUNT, m->nr);
}
+ vcpu_to_pmu(&vmx->vcpu)->global_ctrl_slot_in_autostore = -ENOENT;
}
}

@@ -7236,7 +7240,7 @@ static void vmx_cancel_injection(struct kvm_vcpu *vcpu)
vmcs_write32(VM_ENTRY_INTR_INFO_FIELD, 0);
}

-static void atomic_switch_perf_msrs(struct vcpu_vmx *vmx)
+static void __atomic_switch_perf_msrs(struct vcpu_vmx *vmx)
{
int i, nr_msrs;
struct perf_guest_switch_msr *msrs;
@@ -7259,6 +7263,46 @@ static void atomic_switch_perf_msrs(struct vcpu_vmx *vmx)
msrs[i].host, false);
}

+static void save_perf_global_ctrl_in_passthrough_pmu(struct vcpu_vmx *vmx)
+{
+ struct kvm_pmu *pmu = vcpu_to_pmu(&vmx->vcpu);
+ int i;
+
+ if (vm_exit_controls_get(vmx) & VM_EXIT_SAVE_IA32_PERF_GLOBAL_CTRL) {
+ pmu->global_ctrl = vmcs_read64(GUEST_IA32_PERF_GLOBAL_CTRL);
+ } else {
+ i = pmu->global_ctrl_slot_in_autostore;
+ pmu->global_ctrl = vmx->msr_autostore.guest.val[i].value;
+ }
+}
+
+static void load_perf_global_ctrl_in_passthrough_pmu(struct vcpu_vmx *vmx)
+{
+ struct kvm_pmu *pmu = vcpu_to_pmu(&vmx->vcpu);
+ u64 global_ctrl = pmu->global_ctrl;
+ int i;
+
+ if (vm_entry_controls_get(vmx) & VM_ENTRY_LOAD_IA32_PERF_GLOBAL_CTRL) {
+ vmcs_write64(GUEST_IA32_PERF_GLOBAL_CTRL, global_ctrl);
+ } else {
+ i = pmu->global_ctrl_slot_in_autoload;
+ vmx->msr_autoload.guest.val[i].value = global_ctrl;
+ }
+}
+
+static void __atomic_switch_perf_msrs_in_passthrough_pmu(struct vcpu_vmx *vmx)
+{
+ load_perf_global_ctrl_in_passthrough_pmu(vmx);
+}
+
+static void atomic_switch_perf_msrs(struct vcpu_vmx *vmx)
+{
+ if (is_passthrough_pmu_enabled(&vmx->vcpu))
+ __atomic_switch_perf_msrs_in_passthrough_pmu(vmx);
+ else
+ __atomic_switch_perf_msrs(vmx);
+}
+
static void vmx_update_hv_timer(struct kvm_vcpu *vcpu, bool force_immediate_exit)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
@@ -7369,6 +7413,9 @@ static noinstr void vmx_vcpu_enter_exit(struct kvm_vcpu *vcpu,
vcpu->arch.cr2 = native_read_cr2();
vcpu->arch.regs_avail &= ~VMX_REGS_LAZY_LOAD_SET;

+ if (is_passthrough_pmu_enabled(vcpu))
+ save_perf_global_ctrl_in_passthrough_pmu(vmx);
+
vmx->idt_vectoring_info = 0;

vmx_enable_fb_clear(vmx);
--
2.45.0.rc1.225.g2a3ae87e7f-goog