mirrors/linux
2
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git synced 2026-05-09 10:11:52 -04:00
Code Issues Packages Projects Releases Wiki Activity

KVM: selftests: Precisely mask off dynamic fields in CPUID test

Browse Source 
When comparing vCPU CPUID entries against KVM's supported CPUID, mask off
only the dynamic fields/bits instead of skipping the entire entry.
Precisely masking bits isn't meaningfully more difficult than skipping
entire entries, and will be necessary to maintain test coverage when a
future commit enables OSXSAVE by default, i.e. makes one bit in all of
CPUID.0x1 dynamic.

Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Link: https://lore.kernel.org/r/20241003234337.273364-3-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Sean Christopherson
2024-10-03 16:43:28 -07:00
parent f8912210eb
commit f2c5aa3167
1 changed files with 36 additions and 25 deletions
Download Patch File Download Diff File Expand all files Collapse all files

61
tools/testing/selftests/kvm/x86_64/cpuid_test.c
View File

@@ -12,17 +12,16 @@
#include "kvm_util.h"
#include "processor.h"
/* CPUIDs known to differ */
struct {
u32 function;
u32 index;
} mangled_cpuids[] = {
/*
* These entries depend on the vCPU's XCR0 register and IA32_XSS MSR,
* which are not controlled for by this test.
*/
{.function = 0xd, .index = 0},
{.function = 0xd, .index = 1},
struct cpuid_mask {
union {
struct {
u32 eax;
u32 ebx;
u32 ecx;
u32 edx;
};
u32 regs[4];
};
};
static void test_guest_cpuids(struct kvm_cpuid2 *guest_cpuid)
@@ -56,17 +55,23 @@ static void guest_main(struct kvm_cpuid2 *guest_cpuid)
GUEST_DONE();
}
static bool is_cpuid_mangled(const struct kvm_cpuid_entry2 *entrie)
static struct cpuid_mask get_const_cpuid_mask(const struct kvm_cpuid_entry2 *entry)
{
int i;
struct cpuid_mask mask;
for (i = 0; i < ARRAY_SIZE(mangled_cpuids); i++) {
if (mangled_cpuids[i].function == entrie->function &&
mangled_cpuids[i].index == entrie->index)
return true;
memset(&mask, 0xff, sizeof(mask));
switch (entry->function) {
case 0xd:
/*
* CPUID.0xD.{0,1}.EBX enumerate XSAVE size based on the current
* XCR0 and IA32_XSS MSR values.
*/
if (entry->index < 2)
mask.ebx = 0;
break;
}
return false;
return mask;
}
static void compare_cpuids(const struct kvm_cpuid2 *cpuid1,
@@ -79,6 +84,8 @@ static void compare_cpuids(const struct kvm_cpuid2 *cpuid1,
"CPUID nent mismatch: %d vs. %d", cpuid1->nent, cpuid2->nent);
for (i = 0; i < cpuid1->nent; i++) {
struct cpuid_mask mask;
e1 = &cpuid1->entries[i];
e2 = &cpuid2->entries[i];
@@ -88,15 +95,19 @@ static void compare_cpuids(const struct kvm_cpuid2 *cpuid1,
i, e1->function, e1->index, e1->flags,
e2->function, e2->index, e2->flags);
if (is_cpuid_mangled(e1))
continue;
/* Mask off dynamic bits, e.g. OSXSAVE, when comparing entries. */
mask = get_const_cpuid_mask(e1);
TEST_ASSERT(e1->eax == e2->eax && e1->ebx == e2->ebx &&
e1->ecx == e2->ecx && e1->edx == e2->edx,
TEST_ASSERT((e1->eax & mask.eax) == (e2->eax & mask.eax) &&
(e1->ebx & mask.ebx) == (e2->ebx & mask.ebx) &&
(e1->ecx & mask.ecx) == (e2->ecx & mask.ecx) &&
(e1->edx & mask.edx) == (e2->edx & mask.edx),
"CPUID 0x%x.%x differ: 0x%x:0x%x:0x%x:0x%x vs 0x%x:0x%x:0x%x:0x%x",
e1->function, e1->index,
e1->eax, e1->ebx, e1->ecx, e1->edx,
e2->eax, e2->ebx, e2->ecx, e2->edx);
e1->eax & mask.eax, e1->ebx & mask.ebx,
e1->ecx & mask.ecx, e1->edx & mask.edx,
e2->eax & mask.eax, e2->ebx & mask.ebx,
e2->ecx & mask.ecx, e2->edx & mask.edx);
}
}