linux-kernel - Re: [PATCH v3 25/34] KVM: selftests: Make it possible to replace PTEs with __virt_pg

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Message-ID: <750d5a453beee988904ac57e6637521b308c4e7c.camel@redhat.com>
Date:   Wed, 11 May 2022 14:34:32 +0300
From:   Maxim Levitsky <mlevitsk@...hat.com>
To:     Vitaly Kuznetsov <vkuznets@...hat.com>, kvm@...r.kernel.org,
        Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Michael Kelley <mikelley@...rosoft.com>,
        Siddharth Chandrasekaran <sidcha@...zon.de>,
        linux-hyperv@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 25/34] KVM: selftests: Make it possible to replace
 PTEs with __virt_pg_map()

On Thu, 2022-04-14 at 15:20 +0200, Vitaly Kuznetsov wrote:
> __virt_pg_map() makes an assumption that leaf PTE is not present. This
> is not suitable if the test wants to replace an already present
> PTE. Hyper-V PV TLB flush test is going to need that.
> 
> Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com>
> ---
>  tools/testing/selftests/kvm/include/x86_64/processor.h | 2 +-
>  tools/testing/selftests/kvm/lib/x86_64/processor.c     | 6 +++---
>  tools/testing/selftests/kvm/max_guest_memory_test.c    | 2 +-
>  tools/testing/selftests/kvm/x86_64/mmu_role_test.c     | 2 +-
>  4 files changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/tools/testing/selftests/kvm/include/x86_64/processor.h b/tools/testing/selftests/kvm/include/x86_64/processor.h
> index 9ad7602a257b..c20b18d05119 100644
> --- a/tools/testing/selftests/kvm/include/x86_64/processor.h
> +++ b/tools/testing/selftests/kvm/include/x86_64/processor.h
> @@ -473,7 +473,7 @@ enum x86_page_size {
>  	X86_PAGE_SIZE_1G,
>  };
>  void __virt_pg_map(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr,
> -		   enum x86_page_size page_size);
> +		   enum x86_page_size page_size, bool replace);
>  
>  /*
>   * Basic CPU control in CR0
> diff --git a/tools/testing/selftests/kvm/lib/x86_64/processor.c b/tools/testing/selftests/kvm/lib/x86_64/processor.c
> index 9f000dfb5594..20df3e84d777 100644
> --- a/tools/testing/selftests/kvm/lib/x86_64/processor.c
> +++ b/tools/testing/selftests/kvm/lib/x86_64/processor.c
> @@ -229,7 +229,7 @@ static struct pageUpperEntry *virt_create_upper_pte(struct kvm_vm *vm,
>  }
>  
>  void __virt_pg_map(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr,
> -		   enum x86_page_size page_size)
> +		   enum x86_page_size page_size, bool replace)
>  {
>  	const uint64_t pg_size = 1ull << ((page_size * 9) + 12);
>  	struct pageUpperEntry *pml4e, *pdpe, *pde;
> @@ -270,7 +270,7 @@ void __virt_pg_map(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr,
>  
>  	/* Fill in page table entry. */
>  	pte = virt_get_pte(vm, pde->pfn, vaddr, 0);
> -	TEST_ASSERT(!pte->present,
> +	TEST_ASSERT(replace || !pte->present,
>  		    "PTE already present for 4k page at vaddr: 0x%lx\n", vaddr);
>  	pte->pfn = paddr >> vm->page_shift;
>  	pte->writable = true;
> @@ -279,7 +279,7 @@ void __virt_pg_map(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr,
>  
>  void virt_pg_map(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr)
>  {
> -	__virt_pg_map(vm, vaddr, paddr, X86_PAGE_SIZE_4K);
> +	__virt_pg_map(vm, vaddr, paddr, X86_PAGE_SIZE_4K, false);
>  }
>  
>  static struct pageTableEntry *_vm_get_page_table_entry(struct kvm_vm *vm, int vcpuid,
> diff --git a/tools/testing/selftests/kvm/max_guest_memory_test.c b/tools/testing/selftests/kvm/max_guest_memory_test.c
> index 3875c4b23a04..437f77633b0e 100644
> --- a/tools/testing/selftests/kvm/max_guest_memory_test.c
> +++ b/tools/testing/selftests/kvm/max_guest_memory_test.c
> @@ -244,7 +244,7 @@ int main(int argc, char *argv[])
>  #ifdef __x86_64__
>  		/* Identity map memory in the guest using 1gb pages. */
>  		for (i = 0; i < slot_size; i += size_1gb)
> -			__virt_pg_map(vm, gpa + i, gpa + i, X86_PAGE_SIZE_1G);
> +			__virt_pg_map(vm, gpa + i, gpa + i, X86_PAGE_SIZE_1G, false);
>  #else
>  		for (i = 0; i < slot_size; i += vm_get_page_size(vm))
>  			virt_pg_map(vm, gpa + i, gpa + i);
> diff --git a/tools/testing/selftests/kvm/x86_64/mmu_role_test.c b/tools/testing/selftests/kvm/x86_64/mmu_role_test.c
> index da2325fcad87..e3fdf320b9f4 100644
> --- a/tools/testing/selftests/kvm/x86_64/mmu_role_test.c
> +++ b/tools/testing/selftests/kvm/x86_64/mmu_role_test.c
> @@ -35,7 +35,7 @@ static void mmu_role_test(u32 *cpuid_reg, u32 evil_cpuid_val)
>  	run = vcpu_state(vm, VCPU_ID);
>  
>  	/* Map 1gb page without a backing memlot. */
> -	__virt_pg_map(vm, MMIO_GPA, MMIO_GPA, X86_PAGE_SIZE_1G);
> +	__virt_pg_map(vm, MMIO_GPA, MMIO_GPA, X86_PAGE_SIZE_1G, false);
>  
>  	r = _vcpu_run(vm, VCPU_ID);
>  

Reviewed-by: Maxim Levitsky <mlevitsk@...hat.com>

Best regards,
	Maxim Levitsky