Re: [RFC PATCH v5 22/29] KVM: selftests: Add functions to allow mapping as shared

[Chen, Zide]

On 12/12/2023 12:47 PM, Sagi Shahar wrote:

> 
> 
> -----Original Message-----
> From: Sagi Shahar <sagis@xxxxxxxxxx> 
> Sent: Tuesday, December 12, 2023 12:47 PM
> To: linux-kselftest@xxxxxxxxxxxxxxx; Ackerley Tng <ackerleytng@xxxxxxxxxx>; Afranji, Ryan <afranji@xxxxxxxxxx>; Aktas, Erdem <erdemaktas@xxxxxxxxxx>; Sagi Shahar <sagis@xxxxxxxxxx>; Yamahata, Isaku <isaku.yamahata@xxxxxxxxx>
> Cc: Sean Christopherson <seanjc@xxxxxxxxxx>; Paolo Bonzini <pbonzini@xxxxxxxxxx>; Shuah Khan <shuah@xxxxxxxxxx>; Peter Gonda <pgonda@xxxxxxxxxx>; Xu, Haibo1 <haibo1.xu@xxxxxxxxx>; Chao Peng <chao.p.peng@xxxxxxxxxxxxxxx>; Annapurve, Vishal <vannapurve@xxxxxxxxxx>; Roger Wang <runanwang@xxxxxxxxxx>; Vipin Sharma <vipinsh@xxxxxxxxxx>; jmattson@xxxxxxxxxx; dmatlack@xxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; kvm@xxxxxxxxxxxxxxx; linux-mm@xxxxxxxxx
> Subject: [RFC PATCH v5 22/29] KVM: selftests: Add functions to allow mapping as shared

Since protected_phy_pages is introduced to keep track of the guest
memory's private/shared property, it's better to keep it consistent with
the guest mappings.

Instead of having a set of new APIs to force it to map shared guest
pages, how about to update protected_phy_pages sparsebits right before
the mapping, and just call the existing virt_pg_map() to do the mapping?


> From: Ackerley Tng <ackerleytng@xxxxxxxxxx>
> 
> Signed-off-by: Ackerley Tng <ackerleytng@xxxxxxxxxx>
> Signed-off-by: Ryan Afranji <afranji@xxxxxxxxxx>
> Signed-off-by: Sagi Shahar <sagis@xxxxxxxxxx>
> ---
>  .../selftests/kvm/include/kvm_util_base.h     | 24 ++++++++++++++
>  tools/testing/selftests/kvm/lib/kvm_util.c    | 32 +++++++++++++++++++
>  .../selftests/kvm/lib/x86_64/processor.c      | 15 +++++++--
>  3 files changed, 69 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/testing/selftests/kvm/include/kvm_util_base.h b/tools/testing/selftests/kvm/include/kvm_util_base.h
> index b353617fcdd1..efd7ae8abb20 100644
> --- a/tools/testing/selftests/kvm/include/kvm_util_base.h
> +++ b/tools/testing/selftests/kvm/include/kvm_util_base.h
> @@ -574,6 +574,8 @@ vm_vaddr_t vm_vaddr_alloc_page(struct kvm_vm *vm);
>  
>  void virt_map(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr,
>  	      unsigned int npages);
> +void virt_map_shared(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr,
> +		     unsigned int npages);
>  void *addr_gpa2hva(struct kvm_vm *vm, vm_paddr_t gpa);  void *addr_gva2hva(struct kvm_vm *vm, vm_vaddr_t gva);  vm_paddr_t addr_hva2gpa(struct kvm_vm *vm, void *hva); @@ -1034,6 +1036,28 @@ static inline void virt_pg_map(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr
>  	virt_arch_pg_map(vm, vaddr, paddr);
>  }
>  
> +/*
> + * VM Virtual Page Map as Shared
> + *
> + * Input Args:
> + *   vm - Virtual Machine
> + *   vaddr - VM Virtual Address
> + *   paddr - VM Physical Address
> + *   memslot - Memory region slot for new virtual translation tables
> + *
> + * Output Args: None
> + *
> + * Return: None
> + *
> + * Within @vm, creates a virtual translation for the page starting
> + * at @vaddr to the page starting at @paddr.
> + */
> +void virt_arch_pg_map_shared(struct kvm_vm *vm, uint64_t vaddr, 
> +uint64_t paddr);
> +
> +static inline void virt_pg_map_shared(struct kvm_vm *vm, uint64_t 
> +vaddr, uint64_t paddr) {
> +	virt_arch_pg_map_shared(vm, vaddr, paddr); }
>  
>  /*
>   * Address Guest Virtual to Guest Physical diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
> index 4f1ae0f1eef0..28780fa1f0f2 100644
> --- a/tools/testing/selftests/kvm/lib/kvm_util.c
> +++ b/tools/testing/selftests/kvm/lib/kvm_util.c
> @@ -1573,6 +1573,38 @@ void virt_map(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr,
>  	}
>  }
>  
> +/*
> + * Map a range of VM virtual address to the VM's physical address as 
> +shared
> + *
> + * Input Args:
> + *   vm - Virtual Machine
> + *   vaddr - Virtuall address to map
> + *   paddr - VM Physical Address
> + *   npages - The number of pages to map
> + *
> + * Output Args: None
> + *
> + * Return: None
> + *
> + * Within the VM given by @vm, creates a virtual translation for
> + * @npages starting at @vaddr to the page range starting at @paddr.
> + */
> +void virt_map_shared(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr,
> +		     unsigned int npages)
> +{
> +	size_t page_size = vm->page_size;
> +	size_t size = npages * page_size;
> +
> +	TEST_ASSERT(vaddr + size > vaddr, "Vaddr overflow");
> +	TEST_ASSERT(paddr + size > paddr, "Paddr overflow");
> +
> +	while (npages--) {
> +		virt_pg_map_shared(vm, vaddr, paddr);
> +		vaddr += page_size;
> +		paddr += page_size;
> +	}
> +}
> +
>  /*
>   * Address VM Physical to Host Virtual
>   *
> diff --git a/tools/testing/selftests/kvm/lib/x86_64/processor.c b/tools/testing/selftests/kvm/lib/x86_64/processor.c
> index 566d82829da4..aa2a57ddb8d3 100644
> --- a/tools/testing/selftests/kvm/lib/x86_64/processor.c
> +++ b/tools/testing/selftests/kvm/lib/x86_64/processor.c
> @@ -190,7 +190,8 @@ static uint64_t *virt_create_upper_pte(struct kvm_vm *vm,
>  	return pte;
>  }
>  
> -void __virt_pg_map(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr, int level)
> +static void ___virt_pg_map(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr,
> +			   int level, bool protected)
>  {
>  	const uint64_t pg_size = PG_LEVEL_SIZE(level);
>  	uint64_t *pml4e, *pdpe, *pde;
> @@ -235,17 +236,27 @@ void __virt_pg_map(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr, int level)
>  		    "PTE already present for 4k page at vaddr: 0x%lx\n", vaddr);
>  	*pte = PTE_PRESENT_MASK | PTE_WRITABLE_MASK | (paddr & PHYSICAL_PAGE_MASK);
>  
> -	if (vm_is_gpa_protected(vm, paddr))
> +	if (protected)>  		*pte |= vm->arch.c_bit;
>  	else
>  		*pte |= vm->arch.s_bit;
>  }
>  
> +void __virt_pg_map(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr, 
> +int level) {
> +	___virt_pg_map(vm, vaddr, paddr, level, vm_is_gpa_protected(vm, 
> +paddr)); }
> +
>  void virt_arch_pg_map(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr)  {
>  	__virt_pg_map(vm, vaddr, paddr, PG_LEVEL_4K);  }
>  
> +void virt_arch_pg_map_shared(struct kvm_vm *vm, uint64_t vaddr, 
> +uint64_t paddr) {
> +	___virt_pg_map(vm, vaddr, paddr, PG_LEVEL_4K, false); }

Here, it tries to create the guest mappings regardless of what the value
of protected_phy_pages is, which could create confusion.

> +
>  void virt_map_level(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr,
>  		    uint64_t nr_bytes, int level)
>  {
> --
> 2.43.0.472.g3155946c3a-goog
>