[PATCH 31/42] KVM: selftests: Set input function/index in raw CPUID helper(s)

From: Sean Christopherson
Date: Fri Jun 03 2022 - 21:23:38 EST


Set the function/index for CPUID in the helper instead of relying on the
caller to do so. In addition to reducing the risk of consuming an
uninitialized ECX, having the function/index embedded in the call makes
it easier to understand what is being checked.

Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
.../selftests/kvm/include/x86_64/processor.h | 16 +++++++++++++---
.../selftests/kvm/lib/x86_64/processor.c | 13 ++++---------
tools/testing/selftests/kvm/x86_64/amx_test.c | 19 ++++---------------
.../testing/selftests/kvm/x86_64/cpuid_test.c | 11 +++++------
4 files changed, 26 insertions(+), 33 deletions(-)

diff --git a/tools/testing/selftests/kvm/include/x86_64/processor.h b/tools/testing/selftests/kvm/include/x86_64/processor.h
index 6c14b34014c2..eb4730bf4e77 100644
--- a/tools/testing/selftests/kvm/include/x86_64/processor.h
+++ b/tools/testing/selftests/kvm/include/x86_64/processor.h
@@ -402,10 +402,13 @@ static inline void outl(uint16_t port, uint32_t value)
__asm__ __volatile__("outl %%eax, %%dx" : : "d"(port), "a"(value));
}

-static inline void cpuid(uint32_t *eax, uint32_t *ebx,
- uint32_t *ecx, uint32_t *edx)
+static inline void __cpuid(uint32_t function, uint32_t index,
+ uint32_t *eax, uint32_t *ebx,
+ uint32_t *ecx, uint32_t *edx)
{
- /* ecx is often an input as well as an output. */
+ *eax = function;
+ *ecx = index;
+
asm volatile("cpuid"
: "=a" (*eax),
"=b" (*ebx),
@@ -415,6 +418,13 @@ static inline void cpuid(uint32_t *eax, uint32_t *ebx,
: "memory");
}

+static inline void cpuid(uint32_t function,
+ uint32_t *eax, uint32_t *ebx,
+ uint32_t *ecx, uint32_t *edx)
+{
+ return __cpuid(function, 0, eax, ebx, ecx, edx);
+}
+
#define SET_XMM(__var, __xmm) \
asm volatile("movq %0, %%"#__xmm : : "r"(__var) : #__xmm)

diff --git a/tools/testing/selftests/kvm/lib/x86_64/processor.c b/tools/testing/selftests/kvm/lib/x86_64/processor.c
index 41cc320d3e34..1d92a1d9a03f 100644
--- a/tools/testing/selftests/kvm/lib/x86_64/processor.c
+++ b/tools/testing/selftests/kvm/lib/x86_64/processor.c
@@ -1285,9 +1285,7 @@ unsigned long vm_compute_max_gfn(struct kvm_vm *vm)

/* Before family 17h, the HyperTransport area is just below 1T. */
ht_gfn = (1 << 28) - num_ht_pages;
- eax = 1;
- ecx = 0;
- cpuid(&eax, &ebx, &ecx, &edx);
+ cpuid(1, &eax, &ebx, &ecx, &edx);
if (x86_family(eax) < 0x17)
goto done;

@@ -1296,18 +1294,15 @@ unsigned long vm_compute_max_gfn(struct kvm_vm *vm)
* reduced due to SME by bits 11:6 of CPUID[0x8000001f].EBX. Use
* the old conservative value if MAXPHYADDR is not enumerated.
*/
- eax = 0x80000000;
- cpuid(&eax, &ebx, &ecx, &edx);
+ cpuid(0x80000000, &eax, &ebx, &ecx, &edx);
max_ext_leaf = eax;
if (max_ext_leaf < 0x80000008)
goto done;

- eax = 0x80000008;
- cpuid(&eax, &ebx, &ecx, &edx);
+ cpuid(0x80000008, &eax, &ebx, &ecx, &edx);
max_pfn = (1ULL << ((eax & 0xff) - vm->page_shift)) - 1;
if (max_ext_leaf >= 0x8000001f) {
- eax = 0x8000001f;
- cpuid(&eax, &ebx, &ecx, &edx);
+ cpuid(0x8000001f, &eax, &ebx, &ecx, &edx);
max_pfn >>= (ebx >> 6) & 0x3f;
}

diff --git a/tools/testing/selftests/kvm/x86_64/amx_test.c b/tools/testing/selftests/kvm/x86_64/amx_test.c
index bcf535646321..866a42d07d75 100644
--- a/tools/testing/selftests/kvm/x86_64/amx_test.c
+++ b/tools/testing/selftests/kvm/x86_64/amx_test.c
@@ -122,9 +122,7 @@ static inline void check_cpuid_xsave(void)
{
uint32_t eax, ebx, ecx, edx;

- eax = 1;
- ecx = 0;
- cpuid(&eax, &ebx, &ecx, &edx);
+ cpuid(1, &eax, &ebx, &ecx, &edx);
if (!(ecx & CPUID_XSAVE))
GUEST_ASSERT(!"cpuid: no CPU xsave support!");
if (!(ecx & CPUID_OSXSAVE))
@@ -140,10 +138,7 @@ static bool enum_xtile_config(void)
{
u32 eax, ebx, ecx, edx;

- eax = TILE_CPUID;
- ecx = TILE_PALETTE_CPUID_SUBLEAVE;
-
- cpuid(&eax, &ebx, &ecx, &edx);
+ __cpuid(TILE_CPUID, TILE_PALETTE_CPUID_SUBLEAVE, &eax, &ebx, &ecx, &edx);
if (!eax || !ebx || !ecx)
return false;

@@ -165,10 +160,7 @@ static bool enum_xsave_tile(void)
{
u32 eax, ebx, ecx, edx;

- eax = XSTATE_CPUID;
- ecx = XFEATURE_XTILEDATA;
-
- cpuid(&eax, &ebx, &ecx, &edx);
+ __cpuid(XSTATE_CPUID, XFEATURE_XTILEDATA, &eax, &ebx, &ecx, &edx);
if (!eax || !ebx)
return false;

@@ -183,10 +175,7 @@ static bool check_xsave_size(void)
u32 eax, ebx, ecx, edx;
bool valid = false;

- eax = XSTATE_CPUID;
- ecx = XSTATE_USER_STATE_SUBLEAVE;
-
- cpuid(&eax, &ebx, &ecx, &edx);
+ __cpuid(XSTATE_CPUID, XSTATE_USER_STATE_SUBLEAVE, &eax, &ebx, &ecx, &edx);
if (ebx && ebx <= XSAVE_SIZE)
valid = true;

diff --git a/tools/testing/selftests/kvm/x86_64/cpuid_test.c b/tools/testing/selftests/kvm/x86_64/cpuid_test.c
index 2b8ac307da64..a4c4a5c5762a 100644
--- a/tools/testing/selftests/kvm/x86_64/cpuid_test.c
+++ b/tools/testing/selftests/kvm/x86_64/cpuid_test.c
@@ -31,10 +31,9 @@ static void test_guest_cpuids(struct kvm_cpuid2 *guest_cpuid)
u32 eax, ebx, ecx, edx;

for (i = 0; i < guest_cpuid->nent; i++) {
- eax = guest_cpuid->entries[i].function;
- ecx = guest_cpuid->entries[i].index;
-
- cpuid(&eax, &ebx, &ecx, &edx);
+ __cpuid(guest_cpuid->entries[i].function,
+ guest_cpuid->entries[i].index,
+ &eax, &ebx, &ecx, &edx);

GUEST_ASSERT(eax == guest_cpuid->entries[i].eax &&
ebx == guest_cpuid->entries[i].ebx &&
@@ -46,9 +45,9 @@ static void test_guest_cpuids(struct kvm_cpuid2 *guest_cpuid)

static void test_cpuid_40000000(struct kvm_cpuid2 *guest_cpuid)
{
- u32 eax = 0x40000000, ebx, ecx = 0, edx;
+ u32 eax, ebx, ecx, edx;

- cpuid(&eax, &ebx, &ecx, &edx);
+ cpuid(0x40000000, &eax, &ebx, &ecx, &edx);

GUEST_ASSERT(eax == 0x40000001);
}
--
2.36.1.255.ge46751e96f-goog