Re: [RFC PATCH v5 02/29] KVM: selftests: Expose function that sets up sregs based on VM's mode

[Binbin Wu <binbin.wu@linux.intel.com>]

On 12/13/2023 4:46 AM, Sagi Shahar wrote:
> From: Ackerley Tng <ackerleytng@google.com>
>
> This allows initializing sregs without setting vCPU registers in
> KVM.
>
> No functional change intended.

Reviewed-by: Binbin Wu <binbin.wu@linux.intel.com>

>
> Signed-off-by: Ackerley Tng <ackerleytng@google.com>
> Signed-off-by: Ryan Afranji <afranji@google.com>
> Signed-off-by: Sagi Shahar <sagis@google.com>
> ---
>   .../selftests/kvm/include/x86_64/processor.h  |  2 +
>   .../selftests/kvm/lib/x86_64/processor.c      | 39 ++++++++++---------
>   2 files changed, 23 insertions(+), 18 deletions(-)
>
> diff --git a/tools/testing/selftests/kvm/include/x86_64/processor.h b/tools/testing/selftests/kvm/include/x86_64/processor.h
> index 35fcf4d78dfa..0b8855d68744 100644
> --- a/tools/testing/selftests/kvm/include/x86_64/processor.h
> +++ b/tools/testing/selftests/kvm/include/x86_64/processor.h
> @@ -958,6 +958,8 @@ static inline struct kvm_cpuid2 *allocate_kvm_cpuid2(int nr_entries)
>   void vcpu_init_cpuid(struct kvm_vcpu *vcpu, const struct kvm_cpuid2 *cpuid);
>   void vcpu_set_hv_cpuid(struct kvm_vcpu *vcpu);
>   
> +void vcpu_setup_mode_sregs(struct kvm_vm *vm, struct kvm_sregs *sregs);
> +
>   static inline struct kvm_cpuid_entry2 *__vcpu_get_cpuid_entry(struct kvm_vcpu *vcpu,
>   							      uint32_t function,
>   							      uint32_t index)
> diff --git a/tools/testing/selftests/kvm/lib/x86_64/processor.c b/tools/testing/selftests/kvm/lib/x86_64/processor.c
> index aef1c021c4bb..f130f78a4974 100644
> --- a/tools/testing/selftests/kvm/lib/x86_64/processor.c
> +++ b/tools/testing/selftests/kvm/lib/x86_64/processor.c
> @@ -543,36 +543,39 @@ static void kvm_setup_tss_64bit(struct kvm_vm *vm, struct kvm_segment *segp,
>   	kvm_seg_fill_gdt_64bit(vm, segp);
>   }
>   
> -static void vcpu_setup(struct kvm_vm *vm, struct kvm_vcpu *vcpu)
> +void vcpu_setup_mode_sregs(struct kvm_vm *vm, struct kvm_sregs *sregs)
>   {
> -	struct kvm_sregs sregs;
> -
> -	/* Set mode specific system register values. */
> -	vcpu_sregs_get(vcpu, &sregs);
> -
> -	sregs.idt.limit = 0;
> +	sregs->idt.limit = 0;
>   
> -	kvm_setup_gdt(vm, &sregs.gdt);
> +	kvm_setup_gdt(vm, &sregs->gdt);
>   
>   	switch (vm->mode) {
>   	case VM_MODE_PXXV48_4K_SEV:
>   	case VM_MODE_PXXV48_4K:
> -		sregs.cr0 = X86_CR0_PE | X86_CR0_NE | X86_CR0_PG;
> -		sregs.cr4 |= X86_CR4_PAE | X86_CR4_OSFXSR;
> -		sregs.efer |= (EFER_LME | EFER_LMA | EFER_NX);
> -
> -		kvm_seg_set_unusable(&sregs.ldt);
> -		kvm_seg_set_kernel_code_64bit(vm, DEFAULT_CODE_SELECTOR, &sregs.cs);
> -		kvm_seg_set_kernel_data_64bit(vm, DEFAULT_DATA_SELECTOR, &sregs.ds);
> -		kvm_seg_set_kernel_data_64bit(vm, DEFAULT_DATA_SELECTOR, &sregs.es);
> -		kvm_setup_tss_64bit(vm, &sregs.tr, 0x18);
> +		sregs->cr0 = X86_CR0_PE | X86_CR0_NE | X86_CR0_PG;
> +		sregs->cr4 |= X86_CR4_PAE | X86_CR4_OSFXSR;
> +		sregs->efer |= (EFER_LME | EFER_LMA | EFER_NX);
> +
> +		kvm_seg_set_unusable(&sregs->ldt);
> +		kvm_seg_set_kernel_code_64bit(vm, DEFAULT_CODE_SELECTOR, &sregs->cs);
> +		kvm_seg_set_kernel_data_64bit(vm, DEFAULT_DATA_SELECTOR, &sregs->ds);
> +		kvm_seg_set_kernel_data_64bit(vm, DEFAULT_DATA_SELECTOR, &sregs->es);
> +		kvm_setup_tss_64bit(vm, &sregs->tr, 0x18);
>   		break;
>   
>   	default:
>   		TEST_FAIL("Unknown guest mode, mode: 0x%x", vm->mode);
>   	}
>   
> -	sregs.cr3 = vm->pgd;
> +	sregs->cr3 = vm->pgd;
> +}
> +
> +static void vcpu_setup(struct kvm_vm *vm, struct kvm_vcpu *vcpu)
> +{
> +	struct kvm_sregs sregs;
> +
> +	vcpu_sregs_get(vcpu, &sregs);
> +	vcpu_setup_mode_sregs(vm, &sregs);
>   	vcpu_sregs_set(vcpu, &sregs);
>   }
>