https://github.com/torvalds/linux
Revision 4d7404e5ee0066e9a9e8268675de8a273b568b08 authored by Sean Christopherson on 08 February 2023, 20:42:29 UTC, committed by Paolo Bonzini on 15 February 2023, 13:25:43 UTC
Disable KVM support for virtualizing PMUs on hosts with hybrid PMUs until KVM gains a sane way to enumeration the hybrid vPMU to userspace and/or gains a mechanism to let userspace opt-in to the dangers of exposing a hybrid vPMU to KVM guests. Virtualizing a hybrid PMU, or at least part of a hybrid PMU, is possible, but it requires careful, deliberate configuration from userspace. E.g. to expose full functionality, vCPUs need to be pinned to pCPUs to prevent migrating a vCPU between a big core and a little core, userspace must enumerate a reasonable topology to the guest, and guest CPUID must be curated per vCPU to enumerate accurate vPMU capabilities. The last point is especially problematic, as KVM doesn't control which pCPU it runs on when enumerating KVM's vPMU capabilities to userspace, i.e. userspace can't rely on KVM_GET_SUPPORTED_CPUID in it's current form. Alternatively, userspace could enable vPMU support by enumerating the set of features that are common and coherent across all cores, e.g. by filtering PMU events and restricting guest capabilities. But again, that requires userspace to take action far beyond reflecting KVM's supported feature set into the guest. For now, simply disable vPMU support on hybrid CPUs to avoid inducing seemingly random #GPs in guests, and punt support for hybrid CPUs to a future enabling effort. Reported-by: Jianfeng Gao <jianfeng.gao@intel.com> Cc: stable@vger.kernel.org Cc: Andrew Cooper <Andrew.Cooper3@citrix.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Kan Liang <kan.liang@linux.intel.com> Cc: Andi Kleen <ak@linux.intel.com> Link: https://lore.kernel.org/all/20220818181530.2355034-1-kan.liang@linux.intel.com Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20230208204230.1360502-2-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
1 parent 971cecb
Tip revision: 4d7404e5ee0066e9a9e8268675de8a273b568b08 authored by Sean Christopherson on 08 February 2023, 20:42:29 UTC
KVM: x86/pmu: Disable vPMU support on hybrid CPUs (host PMUs)
KVM: x86/pmu: Disable vPMU support on hybrid CPUs (host PMUs)
Tip revision: 4d7404e
File | Mode | Size |
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Documentation | ||
LICENSES | ||
arch | ||
block | ||
certs | ||
crypto | ||
drivers | ||
fs | ||
include | ||
init | ||
io_uring | ||
ipc | ||
kernel | ||
lib | ||
mm | ||
net | ||
rust | ||
samples | ||
scripts | ||
security | ||
sound | ||
tools | ||
usr | ||
virt | ||
.clang-format | -rw-r--r-- | 20.0 KB |
.cocciconfig | -rw-r--r-- | 59 bytes |
.get_maintainer.ignore | -rw-r--r-- | 151 bytes |
.gitattributes | -rw-r--r-- | 62 bytes |
.gitignore | -rw-r--r-- | 2.0 KB |
.mailmap | -rw-r--r-- | 24.8 KB |
.rustfmt.toml | -rw-r--r-- | 369 bytes |
COPYING | -rw-r--r-- | 496 bytes |
CREDITS | -rw-r--r-- | 99.5 KB |
Kbuild | -rw-r--r-- | 2.5 KB |
Kconfig | -rw-r--r-- | 555 bytes |
MAINTAINERS | -rw-r--r-- | 681.9 KB |
Makefile | -rw-r--r-- | 70.2 KB |
README | -rw-r--r-- | 727 bytes |
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