Commit aebc62b3 authored by Sean Christopherson's avatar Sean Christopherson
Browse files

KVM: selftests: Add support for DIV and IDIV in the fastops test 

Extend the fastops test coverage to DIV and IDIV, specifically to provide
coverage for #DE (divide error) exceptions, as #DE is the only exception
that can occur in KVM's fastops path, i.e. that requires exception fixup.

Link: https://lore.kernel.org/r/20250909202835.333554-5-seanjc@google.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent fe08478b

tools/testing/selftests/kvm/x86/fastops_test.c

+38 −0
Original line number Diff line number Diff line
@@ -92,6 +92,42 @@ 
			ex_flags, insn, shift, (uint64_t)input, flags);			\

})



#define guest_execute_fastop_div(__KVM_ASM_SAFE, insn, __a, __d, __rm, __flags)		\

({											\

	uint64_t ign_error_code;							\

	uint8_t vector;									\

											\

	__asm__ __volatile__(fastop(__KVM_ASM_SAFE(insn " %[denom]"))			\

			     : "+a"(__a), "+d"(__d), flags_constraint(__flags),		\

			       KVM_ASM_SAFE_OUTPUTS(vector, ign_error_code)		\

			     : [denom]"rm"(__rm), bt_constraint(__rm)			\

			     : "cc", "memory", KVM_ASM_SAFE_CLOBBERS);			\

	vector;										\

})



#define guest_test_fastop_div(insn, type_t, __val1, __val2)				\

({											\

	type_t _a = __val1, _d = __val1, rm = __val2;					\

	type_t a = _a, d = _d, ex_a = _a, ex_d = _d;					\

	uint64_t flags, ex_flags;							\

	uint8_t v, ex_v;								\

											\

	ex_v = guest_execute_fastop_div(KVM_ASM_SAFE, insn, ex_a, ex_d, rm, ex_flags);	\

	v = guest_execute_fastop_div(KVM_ASM_SAFE_FEP, insn, a, d, rm, flags);		\

											\

	GUEST_ASSERT_EQ(v, ex_v);							\

	__GUEST_ASSERT(v == ex_v,							\

		       "Wanted vector 0x%x for '%s 0x%lx:0x%lx/0x%lx', got 0x%x",	\

		       ex_v, insn, (uint64_t)_a, (uint64_t)_d, (uint64_t)rm, v);	\

	__GUEST_ASSERT(a == ex_a && d == ex_d,						\

		       "Wanted 0x%lx:0x%lx for '%s 0x%lx:0x%lx/0x%lx', got 0x%lx:0x%lx",\

		       (uint64_t)ex_a, (uint64_t)ex_d, insn, (uint64_t)_a,		\

		       (uint64_t)_d, (uint64_t)rm, (uint64_t)a, (uint64_t)d);		\

	__GUEST_ASSERT(v || ex_v || (flags == ex_flags),				\

			"Wanted flags 0x%lx for '%s  0x%lx:0x%lx/0x%lx', got 0x%lx",	\

			ex_flags, insn, (uint64_t)_a, (uint64_t)_d, (uint64_t)rm, flags);\

})



static const uint64_t vals[] = {

	0,

	1,
@@ -141,6 +177,8 @@ if (sizeof(type_t) != 1) { \ 
			guest_test_fastop_cl("sar" suffix, type_t, vals[i], vals[j]);	\

			guest_test_fastop_cl("shl" suffix, type_t, vals[i], vals[j]);	\

			guest_test_fastop_cl("shr" suffix, type_t, vals[i], vals[j]);	\

											\

			guest_test_fastop_div("div" suffix, type_t, vals[i], vals[j]);	\

		}									\

	}										\

} while (0)