Commit f1382585 authored by Sean Christopherson's avatar Sean Christopherson
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KVM: selftests: Verify KVM preserves userspace writes to "durable" MSRs 

Assert that KVM provides "read what you wrote" semantics for all "durable"
MSRs (for lack of a better name).  The extra coverage is cheap from a
runtime performance perspective, and verifying the behavior in the common
helper avoids gratuitous copy+paste in individual tests.

Note, this affects all tests that set MSRs from userspace!

Link: https://lore.kernel.org/r/20230311004618.920745-13-seanjc@google.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent 22234c24

tools/testing/selftests/kvm/include/x86_64/processor.h

+16 −1
Original line number Diff line number Diff line
@@ -945,12 +945,27 @@ do { \ 
	}									\

} while (0)



/*

 * Returns true if KVM should return the last written value when reading an MSR

 * from userspace, e.g. the MSR isn't a command MSR, doesn't emulate state that

 * is changing, etc.  This is NOT an exhaustive list!  The intent is to filter

 * out MSRs that are not durable _and_ that a selftest wants to write.

 */

static inline bool is_durable_msr(uint32_t msr)

{

	return msr != MSR_IA32_TSC;

}



#define vcpu_set_msr(vcpu, msr, val)							\

do {											\

	uint64_t v = val;								\

	uint64_t r, v = val;								\

											\

	TEST_ASSERT_MSR(_vcpu_set_msr(vcpu, msr, v) == 1,				\

			"KVM_SET_MSRS failed on %s, value = 0x%lx", msr, #msr, v);	\

	if (!is_durable_msr(msr))							\

		break;									\

	r = vcpu_get_msr(vcpu, msr);							\

	TEST_ASSERT_MSR(r == v, "Set %s to '0x%lx', got back '0x%lx'", msr, #msr, v, r);\

} while (0)



void kvm_get_cpu_address_width(unsigned int *pa_bits, unsigned int *va_bits);