linux-kernel - Re: [PATCH 14/18] KVM: selftests: Fold x86's descriptor tables helpers into vcpu_init

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Message-ID: <diqzfrwbkr2f.fsf@ctop-sg.c.googlers.com>
Date: Thu, 28 Mar 2024 02:50:32 +0000
From: Ackerley Tng <ackerleytng@...gle.com>
To: Sean Christopherson <seanjc@...gle.com>, Marc Zyngier <maz@...nel.org>, 
	Oliver Upton <oliver.upton@...ux.dev>, Paolo Bonzini <pbonzini@...hat.com>, 
	Christian Borntraeger <borntraeger@...ux.ibm.com>, Janosch Frank <frankja@...ux.ibm.com>, 
	Claudio Imbrenda <imbrenda@...ux.ibm.com>, Anup Patel <anup@...infault.org>, 
	Paul Walmsley <paul.walmsley@...ive.com>, Palmer Dabbelt <palmer@...belt.com>, 
	Albert Ou <aou@...s.berkeley.edu>
Cc: linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.linux.dev, 
	kvm@...r.kernel.org, kvm-riscv@...ts.infradead.org, 
	linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 14/18] KVM: selftests: Fold x86's descriptor tables
 helpers into vcpu_init_sregs()

Sean Christopherson <seanjc@...gle.com> writes:

> Now that the per-VM, on-demand allocation logic in kvm_setup_gdt() and
> vcpu_init_descriptor_tables() is gone, fold them into vcpu_init_sregs().
>
> Note, both kvm_setup_gdt() and vcpu_init_descriptor_tables() configured the
> GDT, which is why it looks like kvm_setup_gdt() disappears.
>
> Opportunistically delete the pointless zeroing of the IDT limit (it was
> being unconditionally overwritten by vcpu_init_descriptor_tables()).
>
> Signed-off-by: Sean Christopherson <seanjc@...gle.com>
> ---
>  .../selftests/kvm/lib/x86_64/processor.c      | 32 ++++---------------
>  1 file changed, 6 insertions(+), 26 deletions(-)
>
> diff --git a/tools/testing/selftests/kvm/lib/x86_64/processor.c b/tools/testing/selftests/kvm/lib/x86_64/processor.c
> index 561c0aa93608..5cf845975f66 100644
> --- a/tools/testing/selftests/kvm/lib/x86_64/processor.c
> +++ b/tools/testing/selftests/kvm/lib/x86_64/processor.c
> @@ -516,12 +516,6 @@ vm_paddr_t addr_arch_gva2gpa(struct kvm_vm *vm, vm_vaddr_t gva)
>  	return vm_untag_gpa(vm, PTE_GET_PA(*pte)) | (gva & ~HUGEPAGE_MASK(level));
>  }
>  
> -static void kvm_setup_gdt(struct kvm_vm *vm, struct kvm_dtable *dt)
> -{
> -	dt->base = vm->arch.gdt;
> -	dt->limit = getpagesize() - 1;
> -}
> -
>  static void kvm_setup_tss_64bit(struct kvm_vm *vm, struct kvm_segment *segp,
>  				int selector)
>  {
> @@ -537,32 +531,19 @@ static void kvm_setup_tss_64bit(struct kvm_vm *vm, struct kvm_segment *segp,
>  	kvm_seg_fill_gdt_64bit(vm, segp);
>  }
>  
> -static void vcpu_init_descriptor_tables(struct kvm_vcpu *vcpu)
> +static void vcpu_init_sregs(struct kvm_vm *vm, struct kvm_vcpu *vcpu)
>  {
> -	struct kvm_vm *vm = vcpu->vm;
>  	struct kvm_sregs sregs;
>  
> +	TEST_ASSERT_EQ(vm->mode, VM_MODE_PXXV48_4K);
> +
> +	/* Set mode specific system register values. */
>  	vcpu_sregs_get(vcpu, &sregs);
> +
>  	sregs.idt.base = vm->arch.idt;
>  	sregs.idt.limit = NUM_INTERRUPTS * sizeof(struct idt_entry) - 1;
>  	sregs.gdt.base = vm->arch.gdt;
>  	sregs.gdt.limit = getpagesize() - 1;
> -	kvm_seg_set_kernel_data_64bit(NULL, DEFAULT_DATA_SELECTOR, &sregs.gs);
> -	vcpu_sregs_set(vcpu, &sregs);
> -}
> -
> -static void vcpu_init_sregs(struct kvm_vm *vm, struct kvm_vcpu *vcpu)
> -{
> -	struct kvm_sregs sregs;
> -
> -	TEST_ASSERT_EQ(vm->mode, VM_MODE_PXXV48_4K);
> -
> -	/* Set mode specific system register values. */
> -	vcpu_sregs_get(vcpu, &sregs);
> -
> -	sregs.idt.limit = 0;
> -
> -	kvm_setup_gdt(vm, &sregs.gdt);
>  
>  	sregs.cr0 = X86_CR0_PE | X86_CR0_NE | X86_CR0_PG;
>  	sregs.cr4 |= X86_CR4_PAE | X86_CR4_OSFXSR;
> @@ -572,12 +553,11 @@ static void vcpu_init_sregs(struct kvm_vm *vm, struct kvm_vcpu *vcpu)
>  	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_seg_set_kernel_data_64bit(NULL, DEFAULT_DATA_SELECTOR, &sregs.gs);
>  	kvm_setup_tss_64bit(vm, &sregs.tr, 0x18);
>  
>  	sregs.cr3 = vm->pgd;
>  	vcpu_sregs_set(vcpu, &sregs);
> -
> -	vcpu_init_descriptor_tables(vcpu);
>  }
>  
>  static void set_idt_entry(struct kvm_vm *vm, int vector, unsigned long addr,
> -- 
> 2.44.0.291.gc1ea87d7ee-goog

Reviewed-by: Ackerley Tng <ackerleytng@...gle.com>