On 25/09/2017 06:44, Wei Wang wrote:
> Passthrough the LBR stack to the guest, and auto switch the stack MSRs
> upon VMEntry and VMExit.
>
> Signed-off-by: Wei Wang <wei.w.wang@xxxxxxxxx>
This has to be enabled separately for each guest, because it may prevent
live migration to hosts with a different family/model.
Paolo
> ---
> arch/x86/kvm/vmx.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 50 insertions(+)
>
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index 5f5c2f1..35e02a7 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -107,6 +107,9 @@ static u64 __read_mostly host_xss;
> static bool __read_mostly enable_pml = 1;
> module_param_named(pml, enable_pml, bool, S_IRUGO);
>
> +static bool __read_mostly enable_lbrv = 1;
> +module_param_named(lbrv, enable_lbrv, bool, 0444);
> +
> #define KVM_VMX_TSC_MULTIPLIER_MAX 0xffffffffffffffffULL
>
> /* Guest_tsc -> host_tsc conversion requires 64-bit division. */
> @@ -5428,6 +5431,25 @@ static void ept_set_mmio_spte_mask(void)
> VMX_EPT_MISCONFIG_WX_VALUE);
> }
>
> +static void auto_switch_lbr_msrs(struct vcpu_vmx *vmx)
> +{
> + int i;
> + struct perf_lbr_stack lbr_stack;
> +
> + perf_get_lbr_stack(&lbr_stack);
> +
> + add_atomic_switch_msr(vmx, MSR_LBR_SELECT, 0, 0);
> + add_atomic_switch_msr(vmx, lbr_stack.lbr_tos, 0, 0);
> +
> + for (i = 0; i < lbr_stack.lbr_nr; i++) {
> + add_atomic_switch_msr(vmx, lbr_stack.lbr_from + i, 0, 0);
> + add_atomic_switch_msr(vmx, lbr_stack.lbr_to + i, 0, 0);
> + if (lbr_stack.lbr_info)
> + add_atomic_switch_msr(vmx, lbr_stack.lbr_info + i, 0,
> + 0);
> + }
> +}
> +
> #define VMX_XSS_EXIT_BITMAP 0
> /*
> * Sets up the vmcs for emulated real mode.
> @@ -5508,6 +5530,9 @@ static int vmx_vcpu_setup(struct vcpu_vmx *vmx)
>
> add_atomic_switch_msr(vmx, MSR_IA32_DEBUGCTLMSR, 0, 0);
>
> + if (enable_lbrv)
> + auto_switch_lbr_msrs(vmx);
> +
> if (vmcs_config.vmentry_ctrl & VM_ENTRY_LOAD_IA32_PAT)
> vmcs_write64(GUEST_IA32_PAT, vmx->vcpu.arch.pat);
>
> @@ -6721,6 +6746,28 @@ void vmx_enable_tdp(void)
> kvm_enable_tdp();
> }
>
> +static void vmx_passthrough_lbr_msrs(void)
> +{
> + int i;
> + struct perf_lbr_stack lbr_stack;
> +
> + if (perf_get_lbr_stack(&lbr_stack) < 0) {
> + enable_lbrv = false;
> + return;
> + }
> +
> + vmx_disable_intercept_for_msr(MSR_LBR_SELECT, false);
> + vmx_disable_intercept_for_msr(lbr_stack.lbr_tos, false);
> +
> + for (i = 0; i < lbr_stack.lbr_nr; i++) {
> + vmx_disable_intercept_for_msr(lbr_stack.lbr_from + i, false);
> + vmx_disable_intercept_for_msr(lbr_stack.lbr_to + i, false);
> + if (lbr_stack.lbr_info)
> + vmx_disable_intercept_for_msr(lbr_stack.lbr_info + i,
> + false);
> + }
> +}
> +
> static __init int hardware_setup(void)
> {
> int r = -ENOMEM, i, msr;
> @@ -6822,6 +6869,9 @@ static __init int hardware_setup(void)
> vmx_disable_intercept_for_msr(MSR_IA32_SYSENTER_EIP, false);
> vmx_disable_intercept_for_msr(MSR_IA32_DEBUGCTLMSR, false);
>
> + if (enable_lbrv)
> + vmx_passthrough_lbr_msrs();
> +
> memcpy(vmx_msr_bitmap_legacy_x2apic_apicv,
> vmx_msr_bitmap_legacy, PAGE_SIZE);
> memcpy(vmx_msr_bitmap_longmode_x2apic_apicv,
>
