[POC PATCH 3/5] KVM: selftests: Make guest_code_xsave more friendly
From: Ackerley Tng <hidden>
Date: 2026-05-07 20:34:38
Also in:
kvm, linux-coco, linux-doc, linux-kselftest, linux-mm, lkml
Subsystem:
kernel selftest framework, kernel virtual machine (kvm), kernel virtual machine for x86 (kvm/x86), the rest · Maintainers:
Shuah Khan, Paolo Bonzini, Sean Christopherson, Linus Torvalds
The original implementation of guest_code_xsave makes a jmp to guest_sev_es_code in inline assembly. When code that uses guest_sev_es_code is removed, guest_sev_es_code will be optimized out, leading to a linking error since guest_code_xsave still tries to jmp to guest_sev_es_code. Rewrite guest_code_xsave() to instead make a call, in C, to guest_sev_es_code(), so that usage of guest_sev_es_code() is made known to the compiler. This rewriting also gives a name to the xsave inline assembly, improving readability. Signed-off-by: Ackerley Tng <redacted> --- .../selftests/kvm/x86/sev_smoke_test.c | 24 +++++++++++++------ 1 file changed, 17 insertions(+), 7 deletions(-)
diff --git a/tools/testing/selftests/kvm/x86/sev_smoke_test.c b/tools/testing/selftests/kvm/x86/sev_smoke_test.c
index 1a49ee3915864..8b859adf4cf6f 100644
--- a/tools/testing/selftests/kvm/x86/sev_smoke_test.c
+++ b/tools/testing/selftests/kvm/x86/sev_smoke_test.c@@ -80,13 +80,23 @@ static void guest_sev_code(void) GUEST_DONE(); } -/* Stash state passed via VMSA before any compiled code runs. */ -extern void guest_code_xsave(void); -asm("guest_code_xsave:\n" - "mov $" __stringify(XFEATURE_MASK_X87_AVX) ", %eax\n" - "xor %edx, %edx\n" - "xsave (%rdi)\n" - "jmp guest_sev_es_code"); +static void xsave_all_registers(void *addr) +{ + __asm__ __volatile__( + "mov $" __stringify(XFEATURE_MASK_X87_AVX) ", %eax\n" + "xor %edx, %edx\n" + "xsave (%0)" + : + : "r"(addr) + : "eax", "edx", "memory" + ); +} + +static void guest_code_xsave(void *vmsa_gva) +{ + xsave_all_registers(vmsa_gva); + guest_sev_es_code(); +} static void compare_xsave(u8 *from_host, u8 *from_guest) {
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2.54.0.563.g4f69b47b94-goog