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| author | Paolo Bonzini <pbonzini@redhat.com> | 2023-02-27 10:41:46 +0100 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2023-02-27 18:44:57 +0100 |
| commit | 3023c9b4d1092eb27a523c08d9e78cbaec67b59b (patch) | |
| tree | d8ae0596a9013d747f78a78a09cf02c671bcb403 /target | |
| parent | 58794f644e43ef8e60ed05395c58099311c1fcd1 (diff) | |
| download | qemu-3023c9b4d1092eb27a523c08d9e78cbaec67b59b.zip qemu-3023c9b4d1092eb27a523c08d9e78cbaec67b59b.tar.gz qemu-3023c9b4d1092eb27a523c08d9e78cbaec67b59b.tar.bz2 | |
target/i386: KVM: allow fast string operations if host supports them
These are just a flag that documents the performance characteristic of
an instruction; it needs no hypervisor support. So include them even
if KVM does not show them. In particular, FZRM/FSRS/FSRC have only
been added very recently, but they are available on Sapphire Rapids
processors.
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'target')
| -rw-r--r-- | target/i386/kvm/kvm.c | 17 |
1 files changed, 16 insertions, 1 deletions
diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c index 5870301..d18bd2f 100644 --- a/target/i386/kvm/kvm.c +++ b/target/i386/kvm/kvm.c @@ -352,7 +352,7 @@ uint32_t kvm_arch_get_supported_cpuid(KVMState *s, uint32_t function, { struct kvm_cpuid2 *cpuid; uint32_t ret = 0; - uint32_t cpuid_1_edx; + uint32_t cpuid_1_edx, unused; uint64_t bitmask; cpuid = get_supported_cpuid(s); @@ -399,10 +399,20 @@ uint32_t kvm_arch_get_supported_cpuid(KVMState *s, uint32_t function, } else if (function == 6 && reg == R_EAX) { ret |= CPUID_6_EAX_ARAT; /* safe to allow because of emulated APIC */ } else if (function == 7 && index == 0 && reg == R_EBX) { + /* Not new instructions, just an optimization. */ + uint32_t ebx; + host_cpuid(7, 0, &unused, &ebx, &unused, &unused); + ret |= ebx & CPUID_7_0_EBX_ERMS; + if (host_tsx_broken()) { ret &= ~(CPUID_7_0_EBX_RTM | CPUID_7_0_EBX_HLE); } } else if (function == 7 && index == 0 && reg == R_EDX) { + /* Not new instructions, just an optimization. */ + uint32_t edx; + host_cpuid(7, 0, &unused, &unused, &unused, &edx); + ret |= edx & CPUID_7_0_EDX_FSRM; + /* * Linux v4.17-v4.20 incorrectly return ARCH_CAPABILITIES on SVM hosts. * We can detect the bug by checking if MSR_IA32_ARCH_CAPABILITIES is @@ -411,6 +421,11 @@ uint32_t kvm_arch_get_supported_cpuid(KVMState *s, uint32_t function, if (!has_msr_arch_capabs) { ret &= ~CPUID_7_0_EDX_ARCH_CAPABILITIES; } + } else if (function == 7 && index == 1 && reg == R_EAX) { + /* Not new instructions, just an optimization. */ + uint32_t eax; + host_cpuid(7, 1, &eax, &unused, &unused, &unused); + ret |= eax & (CPUID_7_1_EAX_FZRM | CPUID_7_1_EAX_FSRS | CPUID_7_1_EAX_FSRC); } else if (function == 0xd && index == 0 && (reg == R_EAX || reg == R_EDX)) { /* |