[PATCH 6/8] KVM: selftests: Add x86 helpers to play nice with x2APIC MSR #GPs

Sean Christopherson
2024-07-19T23:44:00Z

Add helpers to allow and expect #GP on x2APIC MSRs, and opportunistically
have the existing helper spit out a more useful error message if an
unexpected exception occurs.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
.../selftests/kvm/include/x86_64/apic.h | 21 ++++++++++++++++++-
1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/kvm/include/x86_64/apic.h b/tools/testing/selftests/kvm/include/x86_64/apic.h
index 0f268b55fa06..51990094effd 100644
--- a/tools/testing/selftests/kvm/include/x86_64/apic.h
+++ b/tools/testing/selftests/kvm/include/x86_64/apic.h
@@ -11,6 +11,7 @@
#include <stdint.h>

#include "processor.h"
+#include "ucall_common.h"

#define APIC_DEFAULT_GPA 0xfee00000ULL

@@ -93,9 +94,27 @@ static inline uint64_t x2apic_read_reg(unsigned int reg)
return rdmsr(APIC_BASE_MSR + (reg >> 4));
}

+static inline uint8_t x2apic_write_reg_safe(unsigned int reg, uint64_t value)
+{
+ return wrmsr_safe(APIC_BASE_MSR + (reg >> 4), value);
+}
+
static inline void x2apic_write_reg(unsigned int reg, uint64_t value)
{
- wrmsr(APIC_BASE_MSR + (reg >> 4), value);
+ uint8_t fault = x2apic_write_reg_safe(reg, value);
+
+ __GUEST_ASSERT(!fault, "Unexpected fault 0x%x on WRMSR(%x) = %lx\n",
+ fault, APIC_BASE_MSR + (reg >> 4), value);
}

+static inline void x2apic_write_reg_fault(unsigned int reg, uint64_t value)
+{
+ uint8_t fault = x2apic_write_reg_safe(reg, value);
+
+ __GUEST_ASSERT(fault == GP_VECTOR,
+ "Wanted #GP on WRMSR(%x) = %lx, got 0x%x\n",
+ APIC_BASE_MSR + (reg >> 4), value, fault);
+}
+
+
#endif /* SELFTEST_KVM_APIC_H */
--
2.45.2.1089.g2a221341d9-goog