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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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c11f83e062
The current guest mitigation of TAA is both too heavy and not really sufficient. It is too heavy because it will cause some affected CPUs (those that have MDS_NO but lack TAA_NO) to fall back to VERW and get the corresponding slowdown. It is not really sufficient because it will cause the MDS_NO bit to disappear upon microcode update, so that VMs started before the microcode update will not be runnable anymore afterwards, even with tsx=on. Instead, if tsx=on on the host, we can emulate MSR_IA32_TSX_CTRL for the guest and let it run without the VERW mitigation. Even though MSR_IA32_TSX_CTRL is quite heavyweight, and we do not want to write it on every vmentry, we can use the shared MSR functionality because the host kernel need not protect itself from TSX-based side-channels. Tested-by: Jim Mattson <jmattson@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> |
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| .. | ||
| capabilities.h | ||
| evmcs.c | ||
| evmcs.h | ||
| nested.c | ||
| nested.h | ||
| ops.h | ||
| pmu_intel.c | ||
| vmcs12.c | ||
| vmcs12.h | ||
| vmcs_shadow_fields.h | ||
| vmcs.h | ||
| vmenter.S | ||
| vmx.c | ||
| vmx.h | ||