KVM: selftests: arm64: Check for supported page sizes

Just as arm64 implemenations don't necessary support all IPA
ranges, they don't  all support the same page sizes either. Fun.

Create a dummy VM to snapshot the page sizes supported by the
host, and filter the supported modes.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Link: https://lore.kernel.org/r/20211227124809.1335409-4-maz@kernel.org

tools/testing/selftests/kvm/include/aarch64/processor.h

@@ -113,6 +113,9 @@ enum {
 #define ESR_EC_WP_CURRENT	0x35
 #define ESR_EC_BRK_INS		0x3c
 
+void aarch64_get_supported_page_sizes(uint32_t ipa,
+				      bool *ps4k, bool *ps16k, bool *ps64k);
+
 void vm_init_descriptor_tables(struct kvm_vm *vm);
 void vcpu_init_descriptor_tables(struct kvm_vm *vm, uint32_t vcpuid);
 

tools/testing/selftests/kvm/lib/aarch64/processor.c

@@ -8,6 +8,7 @@
 #include <linux/compiler.h>
 #include <assert.h>
 
+#include "guest_modes.h"
 #include "kvm_util.h"
 #include "../kvm_util_internal.h"
 #include "processor.h"
@@ -433,6 +434,41 @@ uint32_t guest_get_vcpuid(void)
 	return read_sysreg(tpidr_el1);
 }
 
+void aarch64_get_supported_page_sizes(uint32_t ipa,
+				      bool *ps4k, bool *ps16k, bool *ps64k)
+{
+	struct kvm_vcpu_init preferred_init;
+	int kvm_fd, vm_fd, vcpu_fd, err;
+	uint64_t val;
+	struct kvm_one_reg reg = {
+		.id	= KVM_ARM64_SYS_REG(SYS_ID_AA64MMFR0_EL1),
+		.addr	= (uint64_t)&val,
+	};
+
+	kvm_fd = open_kvm_dev_path_or_exit();
+	vm_fd = ioctl(kvm_fd, KVM_CREATE_VM, ipa);
+	TEST_ASSERT(vm_fd >= 0, "Can't create VM");
+
+	vcpu_fd = ioctl(vm_fd, KVM_CREATE_VCPU, 0);
+	TEST_ASSERT(vcpu_fd >= 0, "Can't create vcpu");
+
+	err = ioctl(vm_fd, KVM_ARM_PREFERRED_TARGET, &preferred_init);
+	TEST_ASSERT(err == 0, "Can't get target");
+	err = ioctl(vcpu_fd, KVM_ARM_VCPU_INIT, &preferred_init);
+	TEST_ASSERT(err == 0, "Can't get init vcpu");
+
+	err = ioctl(vcpu_fd, KVM_GET_ONE_REG, &reg);
+	TEST_ASSERT(err == 0, "Can't get MMFR0");
+
+	*ps4k = ((val >> 28) & 0xf) != 0xf;
+	*ps64k = ((val >> 24) & 0xf) == 0;
+	*ps16k = ((val >> 20) & 0xf) != 0;
+
+	close(vcpu_fd);
+	close(vm_fd);
+	close(kvm_fd);
+}
+
 /*
  * arm64 doesn't have a true default mode, so start by computing the
  * available IPA space and page sizes early.

tools/testing/selftests/kvm/lib/guest_modes.c

@@ -5,6 +5,7 @@
 #include "guest_modes.h"
 
 #ifdef __aarch64__
+#include "processor.h"
 enum vm_guest_mode vm_mode_default;
 #endif
 
@@ -17,20 +18,24 @@ void guest_modes_append_default(void)
 #else
 	{
 		unsigned int limit = kvm_check_cap(KVM_CAP_ARM_VM_IPA_SIZE);
+		bool ps4k, ps16k, ps64k;
 		int i;
 
+		aarch64_get_supported_page_sizes(limit, &ps4k, &ps16k, &ps64k);
+
 		vm_mode_default = NUM_VM_MODES;
 
 		if (limit >= 52)
-			guest_mode_append(VM_MODE_P52V48_64K, true, true);
+			guest_mode_append(VM_MODE_P52V48_64K, ps64k, ps64k);
 		if (limit >= 48) {
-			guest_mode_append(VM_MODE_P48V48_4K, true, true);
-			guest_mode_append(VM_MODE_P48V48_64K, true, true);
+			guest_mode_append(VM_MODE_P48V48_4K, ps4k, ps4k);
+			guest_mode_append(VM_MODE_P48V48_64K, ps64k, ps64k);
 		}
 		if (limit >= 40) {
-			guest_mode_append(VM_MODE_P40V48_4K, true, true);
-			guest_mode_append(VM_MODE_P40V48_64K, true, true);
-			vm_mode_default = VM_MODE_P40V48_4K;
+			guest_mode_append(VM_MODE_P40V48_4K, ps4k, ps4k);
+			guest_mode_append(VM_MODE_P40V48_64K, ps64k, ps64k);
+			if (ps4k)
+				vm_mode_default = VM_MODE_P40V48_4K;
 		}
 
 		/*