[PATCH v5 6/6] KVM: selftests: Extend set_sregs_test to cover LASS
From: Sohil Mehta
Date: Thu Oct 15 2026 - 16:26:24 EST
Extend set_sregs_test to cover CR4.LASS and verify that KVM_SET_SREGS
accepts CR4.LASS when LASS is supported, and rejects it, without
modifying sregs, when it isn't.
Signed-off-by: Sohil Mehta <sohil.mehta@xxxxxxxxx>
Tested-by: Kishen Maloor <kishen.maloor@xxxxxxxxx>
Tested-by: Farrah Chen <farrah.chen@xxxxxxxxx>
Reviewed-by: Binbin Wu <binbin.wu@xxxxxxxxxxxxxxx>
---
v5:
- Avoided the CR4 write test specific to LASS.
- Picked up review and test tags
v4:
- New patch
---
tools/testing/selftests/kvm/include/x86/processor.h | 2 ++
tools/testing/selftests/kvm/x86/set_sregs_test.c | 3 +++
2 files changed, 5 insertions(+)
diff --git a/tools/testing/selftests/kvm/include/x86/processor.h b/tools/testing/selftests/kvm/include/x86/processor.h
index 5898a277a2e0..606ee9fe0ddb 100644
--- a/tools/testing/selftests/kvm/include/x86/processor.h
+++ b/tools/testing/selftests/kvm/include/x86/processor.h
@@ -81,6 +81,7 @@ const char *ex_str(int vector);
#define X86_CR4_SMEP (1ul << 20)
#define X86_CR4_SMAP (1ul << 21)
#define X86_CR4_PKE (1ul << 22)
+#define X86_CR4_LASS (1ul << 27)
struct xstate_header {
u64 xstate_bv;
@@ -197,6 +198,7 @@ struct kvm_x86_cpu_feature {
#define X86_FEATURE_SPEC_CTRL KVM_X86_CPU_FEATURE(0x7, 0, EDX, 26)
#define X86_FEATURE_ARCH_CAPABILITIES KVM_X86_CPU_FEATURE(0x7, 0, EDX, 29)
#define X86_FEATURE_PKS KVM_X86_CPU_FEATURE(0x7, 0, ECX, 31)
+#define X86_FEATURE_LASS KVM_X86_CPU_FEATURE(0x7, 1, EAX, 6)
#define X86_FEATURE_XTILECFG KVM_X86_CPU_FEATURE(0xD, 0, EAX, 17)
#define X86_FEATURE_XTILEDATA KVM_X86_CPU_FEATURE(0xD, 0, EAX, 18)
#define X86_FEATURE_XSAVES KVM_X86_CPU_FEATURE(0xD, 1, EAX, 3)
diff --git a/tools/testing/selftests/kvm/x86/set_sregs_test.c b/tools/testing/selftests/kvm/x86/set_sregs_test.c
index 5afc4187f5eb..f30dc61fe00f 100644
--- a/tools/testing/selftests/kvm/x86/set_sregs_test.c
+++ b/tools/testing/selftests/kvm/x86/set_sregs_test.c
@@ -72,6 +72,8 @@ static u64 calc_supported_cr4_feature_bits(void)
cr4 |= X86_CR4_SMAP;
if (kvm_cpu_has(X86_FEATURE_PKU))
cr4 |= X86_CR4_PKE;
+ if (kvm_cpu_has(X86_FEATURE_LASS))
+ cr4 |= X86_CR4_LASS;
return cr4;
}
@@ -128,6 +130,7 @@ static void test_cr_bits(struct kvm_vcpu *vcpu, u64 cr4)
TEST_INVALID_SREG_BIT(vcpu, cr4, sregs, X86_CR4_SMEP);
TEST_INVALID_SREG_BIT(vcpu, cr4, sregs, X86_CR4_SMAP);
TEST_INVALID_SREG_BIT(vcpu, cr4, sregs, X86_CR4_PKE);
+ TEST_INVALID_SREG_BIT(vcpu, cr4, sregs, X86_CR4_LASS);
for (i = 32; i < 64; i++)
TEST_INVALID_SREG_BIT(vcpu, cr0, sregs, BIT(i));
--
2.43.0