linux-kernel - [RFC V1 05/10] KVM: selftests: add support for encrypted vm_vaddr

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Message-Id: <20220715192956.1873315-7-pgonda@google.com>
Date:   Fri, 15 Jul 2022 12:29:51 -0700
From:   Peter Gonda <pgonda@...gle.com>
To:     kvm@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, marcorr@...gle.com,
        seanjc@...gle.com, michael.roth@....com, thomas.lendacky@....com,
        joro@...tes.org, mizhang@...gle.com, pbonzini@...hat.com,
        Peter Gonda <pgonda@...gle.com>
Subject: [RFC V1 05/10] KVM: selftests: add support for encrypted vm_vaddr_* allocations

From: Michael Roth <michael.roth@....com>

The default policy for whether to handle allocations as encrypted or
shared pages is currently determined by vm_phy_pages_alloc(), which in
turn uses the policy defined by vm->memcrypt.enc_by_default.

Test programs may wish to allocate shared vaddrs for things like
sharing memory with the guest. Since enc_by_default will be true in the
case of SEV guests (since it's required in order to have the initial
ELF binary and page table become part of the initial guest payload), an
interface is needed to explicitly request shared pages.

Implement this by splitting the common code out from vm_vaddr_alloc()
and introducing a new vm_vaddr_alloc_shared().

Signed-off-by: Michael Roth <michael.roth@....com>
Signed-off-by: Peter Gonda <pgonda@...gle.com>

---
 .../selftests/kvm/include/kvm_util_base.h     |  1 +
 tools/testing/selftests/kvm/lib/kvm_util.c    | 21 +++++++++++++++----
 2 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/tools/testing/selftests/kvm/include/kvm_util_base.h b/tools/testing/selftests/kvm/include/kvm_util_base.h
index 17eb5fb70867..60b604ac9fa9 100644
--- a/tools/testing/selftests/kvm/include/kvm_util_base.h
+++ b/tools/testing/selftests/kvm/include/kvm_util_base.h
@@ -387,6 +387,7 @@ void vm_mem_region_move(struct kvm_vm *vm, uint32_t slot, uint64_t new_gpa);
 void vm_mem_region_delete(struct kvm_vm *vm, uint32_t slot);
 struct kvm_vcpu *__vm_vcpu_add(struct kvm_vm *vm, uint32_t vcpu_id);
 vm_vaddr_t vm_vaddr_alloc(struct kvm_vm *vm, size_t sz, vm_vaddr_t vaddr_min);
+vm_vaddr_t vm_vaddr_alloc_shared(struct kvm_vm *vm, size_t sz, vm_vaddr_t vaddr_min);
 vm_vaddr_t vm_vaddr_alloc_pages(struct kvm_vm *vm, int nr_pages);
 vm_vaddr_t vm_vaddr_alloc_page(struct kvm_vm *vm);
 
diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
index 5b473a8c90ae..17d9a2606cc8 100644
--- a/tools/testing/selftests/kvm/lib/kvm_util.c
+++ b/tools/testing/selftests/kvm/lib/kvm_util.c
@@ -1250,12 +1250,13 @@ static vm_vaddr_t vm_vaddr_unused_gap(struct kvm_vm *vm, size_t sz,
 }
 
 /*
- * VM Virtual Address Allocate
+ * VM Virtual Address Allocate Shared/Encrypted
  *
  * Input Args:
  *   vm - Virtual Machine
  *   sz - Size in bytes
  *   vaddr_min - Minimum starting virtual address
+ *   encrypt - Whether the region should be handled as encrypted
  *
  * Output Args: None
  *
@@ -1268,13 +1269,15 @@ static vm_vaddr_t vm_vaddr_unused_gap(struct kvm_vm *vm, size_t sz,
  * a unique set of pages, with the minimum real allocation being at least
  * a page.
  */
-vm_vaddr_t vm_vaddr_alloc(struct kvm_vm *vm, size_t sz, vm_vaddr_t vaddr_min)
+static vm_vaddr_t
+_vm_vaddr_alloc(struct kvm_vm *vm, size_t sz, vm_vaddr_t vaddr_min, bool encrypt)
 {
 	uint64_t pages = (sz >> vm->page_shift) + ((sz % vm->page_size) != 0);
 
 	virt_pgd_alloc(vm);
-	vm_paddr_t paddr = vm_phy_pages_alloc(vm, pages,
-					      KVM_UTIL_MIN_PFN * vm->page_size, 0);
+	vm_paddr_t paddr = _vm_phy_pages_alloc(vm, pages,
+					       KVM_UTIL_MIN_PFN * vm->page_size,
+					       0, encrypt);
 
 	/*
 	 * Find an unused range of virtual page addresses of at least
@@ -1295,6 +1298,16 @@ vm_vaddr_t vm_vaddr_alloc(struct kvm_vm *vm, size_t sz, vm_vaddr_t vaddr_min)
 	return vaddr_start;
 }
 
+vm_vaddr_t vm_vaddr_alloc(struct kvm_vm *vm, size_t sz, vm_vaddr_t vaddr_min)
+{
+	return _vm_vaddr_alloc(vm, sz, vaddr_min, vm->memcrypt.enc_by_default);
+}
+
+vm_vaddr_t vm_vaddr_alloc_shared(struct kvm_vm *vm, size_t sz, vm_vaddr_t vaddr_min)
+{
+	return _vm_vaddr_alloc(vm, sz, vaddr_min, false);
+}
+
 /*
  * VM Virtual Address Allocate Pages
  *
-- 
2.37.0.170.g444d1eabd0-goog