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Thanks,
Uros.
On Thu, Oct 29, 2020 at 2:41 PM Uros Bizjak <ubizjak@xxxxxxxxx> wrote:
>
> Replace inline assembly in nested_vmx_check_vmentry_hw
> with a call to __vmx_vcpu_run. The function is not
> performance critical, so (double) GPR save/restore
> in __vmx_vcpu_run can be tolerated, as far as performance
> effects are concerned.
>
> Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> Cc: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
> Signed-off-by: Uros Bizjak <ubizjak@xxxxxxxxx>
> ---
> arch/x86/kvm/vmx/nested.c | 32 +++-----------------------------
> arch/x86/kvm/vmx/vmx.c | 2 --
> arch/x86/kvm/vmx/vmx.h | 1 +
> 3 files changed, 4 insertions(+), 31 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
> index 89af692deb7e..6ab62bf277c4 100644
> --- a/arch/x86/kvm/vmx/nested.c
> +++ b/arch/x86/kvm/vmx/nested.c
> @@ -12,6 +12,7 @@
> #include "nested.h"
> #include "pmu.h"
> #include "trace.h"
> +#include "vmx.h"
> #include "x86.h"
>
> static bool __read_mostly enable_shadow_vmcs = 1;
> @@ -3056,35 +3057,8 @@ static int nested_vmx_check_vmentry_hw(struct kvm_vcpu *vcpu)
> vmx->loaded_vmcs->host_state.cr4 = cr4;
> }
>
> - asm(
> - "sub $%c[wordsize], %%" _ASM_SP "\n\t" /* temporarily adjust RSP for CALL */
> - "cmp %%" _ASM_SP ", %c[host_state_rsp](%[loaded_vmcs]) \n\t"
> - "je 1f \n\t"
> - __ex("vmwrite %%" _ASM_SP ", %[HOST_RSP]") "\n\t"
> - "mov %%" _ASM_SP ", %c[host_state_rsp](%[loaded_vmcs]) \n\t"
> - "1: \n\t"
> - "add $%c[wordsize], %%" _ASM_SP "\n\t" /* un-adjust RSP */
> -
> - /* Check if vmlaunch or vmresume is needed */
> - "cmpb $0, %c[launched](%[loaded_vmcs])\n\t"
> -
> - /*
> - * VMLAUNCH and VMRESUME clear RFLAGS.{CF,ZF} on VM-Exit, set
> - * RFLAGS.CF on VM-Fail Invalid and set RFLAGS.ZF on VM-Fail
> - * Valid. vmx_vmenter() directly "returns" RFLAGS, and so the
> - * results of VM-Enter is captured via CC_{SET,OUT} to vm_fail.
> - */
> - "call vmx_vmenter\n\t"
> -
> - CC_SET(be)
> - : ASM_CALL_CONSTRAINT, CC_OUT(be) (vm_fail)
> - : [HOST_RSP]"r"((unsigned long)HOST_RSP),
> - [loaded_vmcs]"r"(vmx->loaded_vmcs),
> - [launched]"i"(offsetof(struct loaded_vmcs, launched)),
> - [host_state_rsp]"i"(offsetof(struct loaded_vmcs, host_state.rsp)),
> - [wordsize]"i"(sizeof(ulong))
> - : "memory"
> - );
> + vm_fail = __vmx_vcpu_run(vmx, (unsigned long *)&vcpu->arch.regs,
> + vmx->loaded_vmcs->launched);
>
> if (vmx->msr_autoload.host.nr)
> vmcs_write32(VM_EXIT_MSR_LOAD_COUNT, vmx->msr_autoload.host.nr);
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index d14c94d0aff1..0f390c748b18 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -6591,8 +6591,6 @@ static fastpath_t vmx_exit_handlers_fastpath(struct kvm_vcpu *vcpu)
> }
> }
>
> -bool __vmx_vcpu_run(struct vcpu_vmx *vmx, unsigned long *regs, bool launched);
> -
> static noinstr void vmx_vcpu_enter_exit(struct kvm_vcpu *vcpu,
> struct vcpu_vmx *vmx)
> {
> diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
> index f6f66e5c6510..32db3b033e9b 100644
> --- a/arch/x86/kvm/vmx/vmx.h
> +++ b/arch/x86/kvm/vmx/vmx.h
> @@ -339,6 +339,7 @@ void vmx_set_virtual_apic_mode(struct kvm_vcpu *vcpu);
> struct vmx_uret_msr *vmx_find_uret_msr(struct vcpu_vmx *vmx, u32 msr);
> void pt_update_intercept_for_msr(struct kvm_vcpu *vcpu);
> void vmx_update_host_rsp(struct vcpu_vmx *vmx, unsigned long host_rsp);
> +bool __vmx_vcpu_run(struct vcpu_vmx *vmx, unsigned long *regs, bool launched);
> int vmx_find_loadstore_msr_slot(struct vmx_msrs *m, u32 msr);
> void vmx_ept_load_pdptrs(struct kvm_vcpu *vcpu);
>
> --
> 2.26.2
>
