On 8/1/2024 12:58 PM, Mingwei Zhang wrote:
> From: Xiong Zhang <xiong.y.zhang@xxxxxxxxxxxxxxx>
>
> 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.
>
> Co-developed-by: Mingwei Zhang <mizhang@xxxxxxxxxx>
> Signed-off-by: Mingwei Zhang <mizhang@xxxxxxxxxx>
> Signed-off-by: Dapeng Mi <dapeng1.mi@xxxxxxxxxxxxxxx>
> Signed-off-by: Xiong Zhang <xiong.y.zhang@xxxxxxxxxxxxxxx>
> Tested-by: Yongwei Ma <yongwei.ma@xxxxxxxxx>
> ---
> 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 93c17da8271d..7bf901a53543 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -601,6 +601,8 @@ 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 41102658ed21..b126de6569c8 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -4430,6 +4430,7 @@ 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.
> @@ -4457,6 +4458,7 @@ 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)) {
> @@ -4467,6 +4469,7 @@ 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;
> @@ -4485,6 +4488,7 @@ 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;
> }
> }
>
> @@ -7272,7 +7276,7 @@ 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;
> @@ -7295,6 +7299,46 @@ 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;
> + }
When GLOBAL_CTRL MSR is in interception mode, if guest global_ctrl contains
some invalid bit, there may be issue here. The saved guest_ctrl here would
be restored in vm-entry, and it would contains invalid bit as well.
It looks we need to only save valid bits of guest global_ctrl here.
> +}
> +
> +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);
> @@ -7405,6 +7449,9 @@ 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);
