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[PATCH v8 23/30] KVM: selftests: Add functions to allow mapping as shared

Sagi Shahar posted 30 patches 1 month, 4 weeks ago
There is a newer version of this series
[PATCH v8 23/30] KVM: selftests: Add functions to allow mapping as shared
Posted by Sagi Shahar 1 month, 4 weeks ago 
From: Ackerley Tng <ackerleytng@google.com>

virt_map() enforces a private mapping for private memory. Introduce
virt_map_shared() that creates a shared mapping for private as
well as shared memory. This way, the TD does not have to remap its
page tables at runtime.

Signed-off-by: Ackerley Tng <ackerleytng@google.com>
Signed-off-by: Sagi Shahar <sagis@google.com>
---
 .../testing/selftests/kvm/include/kvm_util.h  | 23 +++++++++++++
 tools/testing/selftests/kvm/lib/kvm_util.c    | 34 +++++++++++++++++++
 .../testing/selftests/kvm/lib/x86/processor.c | 15 ++++++--
 3 files changed, 70 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h
index 0d1f24c9f7c7..2e444c172261 100644
--- a/tools/testing/selftests/kvm/include/kvm_util.h
+++ b/tools/testing/selftests/kvm/include/kvm_util.h
@@ -662,6 +662,8 @@ 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);
@@ -1137,6 +1139,27 @@ 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
+ *
+ * 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 f7e00ea0b211..14edb1de5434 100644
--- a/tools/testing/selftests/kvm/lib/kvm_util.c
+++ b/tools/testing/selftests/kvm/lib/kvm_util.c
@@ -7,6 +7,7 @@
 #include "test_util.h"
 #include "kvm_util.h"
 #include "processor.h"
+#include "sparsebit.h"
 #include "ucall_common.h"
 
 #include <assert.h>
@@ -1621,6 +1622,39 @@ 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 - Virtual 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);
+		sparsebit_set(vm->vpages_mapped, vaddr >> vm->page_shift);
+		vaddr += page_size;
+		paddr += page_size;
+	}
+}
+
 /*
  * Address VM Physical to Host Virtual
  *
diff --git a/tools/testing/selftests/kvm/lib/x86/processor.c b/tools/testing/selftests/kvm/lib/x86/processor.c
index 3977719c7893..7742c01d48b1 100644
--- a/tools/testing/selftests/kvm/lib/x86/processor.c
+++ b/tools/testing/selftests/kvm/lib/x86/processor.c
@@ -181,7 +181,8 @@ 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;
@@ -231,17 +232,27 @@ void __virt_pg_map(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr, int level)
 	 * Neither SEV nor TDX supports shared page tables, so only the final
 	 * leaf PTE needs manually set the C/S-bit.
 	 */
-	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);
+}
+
 void virt_map_level(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr,
 		    uint64_t nr_bytes, int level)
 {
-- 
2.51.0.rc0.155.g4a0f42376b-goog
Re: [PATCH v8 23/30] KVM: selftests: Add functions to allow mapping as shared
Posted by Binbin Wu 1 month, 3 weeks ago 

On 8/8/2025 4:16 AM, Sagi Shahar wrote:
> From: Ackerley Tng <ackerleytng@google.com>
>
> virt_map() enforces a private mapping for private memory. Introduce
> virt_map_shared() that creates a shared mapping for private as
> well as shared memory. This way, the TD does not have to remap its
> page tables at runtime.
>
> Signed-off-by: Ackerley Tng <ackerleytng@google.com>
> Signed-off-by: Sagi Shahar <sagis@google.com>
> ---
>   .../testing/selftests/kvm/include/kvm_util.h  | 23 +++++++++++++
>   tools/testing/selftests/kvm/lib/kvm_util.c    | 34 +++++++++++++++++++
>   .../testing/selftests/kvm/lib/x86/processor.c | 15 ++++++--
>   3 files changed, 70 insertions(+), 2 deletions(-)
>
[...]
>   
> -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;
> @@ -231,17 +232,27 @@ void __virt_pg_map(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr, int level)
>   	 * Neither SEV nor TDX supports shared page tables, so only the final
>   	 * leaf PTE needs manually set the C/S-bit.
>   	 */
> -	if (vm_is_gpa_protected(vm, paddr))

Since the original code has already create shared/private mapping based on the
paddr, why not just use virt_map() and shared GPA as paddr, then no need to
duplicate the code?

> +	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);
> +}
> +
>   void virt_map_level(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr,
>   		    uint64_t nr_bytes, int level)
>   {
Re: [PATCH v8 23/30] KVM: selftests: Add functions to allow mapping as shared
Posted by Ira Weiny 1 month, 3 weeks ago 
Sagi Shahar wrote:
> From: Ackerley Tng <ackerleytng@google.com>
> 
> virt_map() enforces a private mapping for private memory. Introduce
> virt_map_shared() that creates a shared mapping for private as
> well as shared memory. This way, the TD does not have to remap its
> page tables at runtime.
> 
> Signed-off-by: Ackerley Tng <ackerleytng@google.com>
> Signed-off-by: Sagi Shahar <sagis@google.com>
> ---
>  .../testing/selftests/kvm/include/kvm_util.h  | 23 +++++++++++++
>  tools/testing/selftests/kvm/lib/kvm_util.c    | 34 +++++++++++++++++++
>  .../testing/selftests/kvm/lib/x86/processor.c | 15 ++++++--
>  3 files changed, 70 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h
> index 0d1f24c9f7c7..2e444c172261 100644
> --- a/tools/testing/selftests/kvm/include/kvm_util.h
> +++ b/tools/testing/selftests/kvm/include/kvm_util.h

[snip]

> +/*
> + * VM Virtual Page Map as Shared
> + *
> + * Input Args:
> + *   vm - Virtual Machine
> + *   vaddr - VM Virtual Address
> + *   paddr - VM Physical Address
> + *
> + * 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

[snip]

> diff --git a/tools/testing/selftests/kvm/lib/x86/processor.c b/tools/testing/selftests/kvm/lib/x86/processor.c
> index 3977719c7893..7742c01d48b1 100644
> --- a/tools/testing/selftests/kvm/lib/x86/processor.c
> +++ b/tools/testing/selftests/kvm/lib/x86/processor.c
> @@ -181,7 +181,8 @@ static uint64_t *virt_create_upper_pte(struct kvm_vm *vm,
>  	return pte;
>  }
>  

[snip]

>  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);
> +}

What about non-x86 arch'es?  How does this compile for them?

Ira

> +
>  void virt_map_level(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr,
>  		    uint64_t nr_bytes, int level)
>  {
> -- 
> 2.51.0.rc0.155.g4a0f42376b-goog
>

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