diff options
| author | Dave Airlie <airlied@redhat.com> | 2022-05-03 16:08:48 +1000 |
|---|---|---|
| committer | Dave Airlie <airlied@redhat.com> | 2022-05-03 16:08:48 +1000 |
| commit | e954d2c94d007afe487044ecfa48f2518643df0e (patch) | |
| tree | 7903ee4cf7d9387e5bb5285f86a2a82b2eacab44 /arch/x86/kvm/cpuid.c | |
| parent | 15e2b419a83777ef652bf5f0ea4385ef7711f710 (diff) | |
| parent | 672c0c5173427e6b3e2a9bbb7be51ceeec78093a (diff) | |
Backmerge tag 'v5.18-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux into drm-next
Linux 5.18-rc5
There was a build fix for arm I wanted in drm-next, so backmerge rather then cherry-pick.
Signed-off-by: Dave Airlie <airlied@redhat.com>
Diffstat (limited to 'arch/x86/kvm/cpuid.c')
| -rw-r--r-- | arch/x86/kvm/cpuid.c | 19 |
1 files changed, 14 insertions, 5 deletions
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index b24ca7f4ed7c..598334ed5fbc 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -1085,12 +1085,21 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function) case 0x80000000: entry->eax = min(entry->eax, 0x80000021); /* - * Serializing LFENCE is reported in a multitude of ways, - * and NullSegClearsBase is not reported in CPUID on Zen2; - * help userspace by providing the CPUID leaf ourselves. + * Serializing LFENCE is reported in a multitude of ways, and + * NullSegClearsBase is not reported in CPUID on Zen2; help + * userspace by providing the CPUID leaf ourselves. + * + * However, only do it if the host has CPUID leaf 0x8000001d. + * QEMU thinks that it can query the host blindly for that + * CPUID leaf if KVM reports that it supports 0x8000001d or + * above. The processor merrily returns values from the + * highest Intel leaf which QEMU tries to use as the guest's + * 0x8000001d. Even worse, this can result in an infinite + * loop if said highest leaf has no subleaves indexed by ECX. */ - if (static_cpu_has(X86_FEATURE_LFENCE_RDTSC) - || !static_cpu_has_bug(X86_BUG_NULL_SEG)) + if (entry->eax >= 0x8000001d && + (static_cpu_has(X86_FEATURE_LFENCE_RDTSC) + || !static_cpu_has_bug(X86_BUG_NULL_SEG))) entry->eax = max(entry->eax, 0x80000021); break; case 0x80000001: |