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i386/kvm: Blacklist TSX on known broken hosts 

Some Intel CPUs are known to have a broken TSX implementation. A
microcode update from Intel disabled TSX on those CPUs, but
GET_SUPPORTED_CPUID might be reporting it as supported if the
hosts were not updated yet.

Manually fixup the GET_SUPPORTED_CPUID data to ensure we will
never enable TSX when running on those hosts.

Reference:
* glibc commit 2702856bf45c82cf8e69f2064f5aa15c0ceb6359:
  https://sourceware.org/git/?p=glibc.git;a=commit;h=2702856bf45c82cf8e69f2064f5aa15c0ceb6359

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Message-Id: <20170309181212.18864-3-ehabkost@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
master
Eduardo Habkost 2017-03-09 15:12:11 -03:00
parent 20271d4840
commit 40e80ee411
1 changed files with 17 additions and 0 deletions
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17
target/i386/kvm.c
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@ -266,6 +266,19 @@ static int get_para_features(KVMState *s)
return features;
}
static bool host_tsx_blacklisted(void)
{
int family, model, stepping;\
char vendor[CPUID_VENDOR_SZ + 1];
host_vendor_fms(vendor, &family, &model, &stepping);
/* Check if we are running on a Haswell host known to have broken TSX */
return !strcmp(vendor, CPUID_VENDOR_INTEL) &&
(family == 6) &&
((model == 63 && stepping < 4) ||
model == 60 || model == 69 || model == 70);
}
/* Returns the value for a specific register on the cpuid entry
*/
@ -349,6 +362,10 @@ 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) {
if (host_tsx_blacklisted()) {
ret &= ~(CPUID_7_0_EBX_RTM | CPUID_7_0_EBX_HLE);
}
} else if (function == 0x80000001 && reg == R_EDX) {
/* On Intel, kvm returns cpuid according to the Intel spec,
* so add missing bits according to the AMD spec: