KVM: selftests: Add library for creating and interacting with SEV guests

Add a library/APIs for creating and interfacing with SEV guests, all of
which need some amount of common functionality, e.g. an open file handle
for the SEV driver (/dev/sev), ioctl() wrappers to pass said file handle
to KVM, tracking of the C-bit, etc.

Add an x86-specific hook to initialize address properties, a.k.a. the
location of the C-bit.  An arch specific hook is rather gross, but x86
already has a dedicated #ifdef-protected kvm_get_cpu_address_width() hook,
i.e. the ugliest code already exists.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: Vishal Annapurve <vannapurve@google.com>
Cc: Ackerly Tng <ackerleytng@google.com>
cc: Andrew Jones <andrew.jones@linux.dev>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Michael Roth <michael.roth@amd.com>
Tested-by: Carlos Bilbao <carlos.bilbao@amd.com>
Originally-by: Michael Roth <michael.roth@amd.com>
Signed-off-by: Peter Gonda <pgonda@google.com>
Co-developed-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20240223004258.3104051-9-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

1 files changed, 17 insertions, 0 deletions

diff --git a/tools/testing/selftests/kvm/lib/x86_64/processor.c b/tools/testing/selftests/kvm/lib/x86_64/processor.c
index 534f36a8a5e8..f1139ba35112 100644
--- a/tools/testing/selftests/kvm/lib/x86_64/processor.c
+++ b/tools/testing/selftests/kvm/lib/x86_64/processor.c
@@ -9,6 +9,7 @@
 #include "test_util.h"
 #include "kvm_util.h"
 #include "processor.h"
+#include "sev.h"
 
 #ifndef NUM_INTERRUPTS
 #define NUM_INTERRUPTS 256
@@ -278,6 +279,9 @@ uint64_t *__vm_get_page_table_entry(struct kvm_vm *vm, uint64_t vaddr,
 {
 	uint64_t *pml4e, *pdpe, *pde;
 
+	TEST_ASSERT(!vm->arch.is_pt_protected,
+		    "Walking page tables of protected guests is impossible");
+
 	TEST_ASSERT(*level >= PG_LEVEL_NONE && *level < PG_LEVEL_NUM,
 		    "Invalid PG_LEVEL_* '%d'", *level);
 
@@ -573,6 +577,11 @@ void kvm_arch_vm_post_create(struct kvm_vm *vm)
 	vm_create_irqchip(vm);
 	sync_global_to_guest(vm, host_cpu_is_intel);
 	sync_global_to_guest(vm, host_cpu_is_amd);
+
+	if (vm->subtype == VM_SUBTYPE_SEV)
+		sev_vm_init(vm);
+	else if (vm->subtype == VM_SUBTYPE_SEV_ES)
+		sev_es_vm_init(vm);
 }
 
 void vcpu_arch_set_entry_point(struct kvm_vcpu *vcpu, void *guest_code)
@@ -1061,6 +1070,14 @@ void kvm_get_cpu_address_width(unsigned int *pa_bits, unsigned int *va_bits)
 	}
 }
 
+void kvm_init_vm_address_properties(struct kvm_vm *vm)
+{
+	if (vm->subtype == VM_SUBTYPE_SEV) {
+		vm->arch.c_bit = BIT_ULL(this_cpu_property(X86_PROPERTY_SEV_C_BIT));
+		vm->gpa_tag_mask = vm->arch.c_bit;
+	}
+}
+
 static void set_idt_entry(struct kvm_vm *vm, int vector, unsigned long addr,
 			  int dpl, unsigned short selector)
 {