[PATCH v2 5/6] selftests: KVM: extract lidt into helper function

[Ivan Orlov <iorlov@amazon.com>]

Implement a function for setting the IDT descriptor from the guest
code. Replace the existing lidt occurrences with calls to this function
as `lidt` is used in multiple places.

Signed-off-by: Ivan Orlov <iorlov@amazon.com>
---
V1 -> V2:
- This patch wasn't included in V1.

 tools/testing/selftests/kvm/include/x86_64/processor.h | 5 +++++
 tools/testing/selftests/kvm/set_memory_region_test.c   | 2 +-
 tools/testing/selftests/kvm/x86_64/sev_smoke_test.c    | 2 +-
 3 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/kvm/include/x86_64/processor.h b/tools/testing/selftests/kvm/include/x86_64/processor.h
index e247f99e0473..1a60c99b5833 100644
--- a/tools/testing/selftests/kvm/include/x86_64/processor.h
+++ b/tools/testing/selftests/kvm/include/x86_64/processor.h
@@ -571,6 +571,11 @@ static inline void set_cr4(uint64_t val)
 	__asm__ __volatile__("mov %0, %%cr4" : : "r" (val) : "memory");
 }
 
+static inline void set_idt(const struct desc_ptr *idt_desc)
+{
+	__asm__ __volatile__("lidt %0"::"m"(*idt_desc));
+}
+
 static inline u64 xgetbv(u32 index)
 {
 	u32 eax, edx;
diff --git a/tools/testing/selftests/kvm/set_memory_region_test.c b/tools/testing/selftests/kvm/set_memory_region_test.c
index a8267628e9ed..a1c53cc854a5 100644
--- a/tools/testing/selftests/kvm/set_memory_region_test.c
+++ b/tools/testing/selftests/kvm/set_memory_region_test.c
@@ -235,7 +235,7 @@ static void guest_code_delete_memory_region(void)
 	 * in the guest will never succeed, and so isn't an option.
 	 */
 	memset(&idt, 0, sizeof(idt));
-	__asm__ __volatile__("lidt %0" :: "m"(idt));
+	set_idt(&idt);
 
 	GUEST_SYNC(0);
 
diff --git a/tools/testing/selftests/kvm/x86_64/sev_smoke_test.c b/tools/testing/selftests/kvm/x86_64/sev_smoke_test.c
index 2e9197eb1652..8c33e02a3183 100644
--- a/tools/testing/selftests/kvm/x86_64/sev_smoke_test.c
+++ b/tools/testing/selftests/kvm/x86_64/sev_smoke_test.c
@@ -166,7 +166,7 @@ static void guest_shutdown_code(void)
 
 	/* Clobber the IDT so that #UD is guaranteed to trigger SHUTDOWN. */
 	memset(&idt, 0, sizeof(idt));
-	__asm__ __volatile__("lidt %0" :: "m"(idt));
+	set_idt(&idt);
 
 	__asm__ __volatile__("ud2");
 }
-- 
2.43.0