diff options
| author | Sean Christopherson <seanjc@google.com> | 2023-11-09 18:28:57 -0800 |
|---|---|---|
| committer | Sean Christopherson <seanjc@google.com> | 2024-02-01 09:35:48 -0800 |
| commit | 83bdfe04c968e0fe3181e4cd41b764e17ac73911 (patch) | |
| tree | 1ed26527de1b6e3f979289519879d7299e9c4c3f /arch/x86/kvm/pmu.c | |
| parent | e35529fb4ac930a4a39e0c15bafcb28a30d26611 (diff) | |
KVM: x86/pmu: Avoid CPL lookup if PMC enabline for USER and KERNEL is the same
Don't bother querying the CPL if a PMC is (not) counting for both USER and
KERNEL, i.e. if the end result is guaranteed to be the same regardless of
the CPL. Querying the CPL on Intel requires a VMREAD, i.e. isn't free,
and a single CMP+Jcc is cheap.
Link: https://lore.kernel.org/r/20231110022857.1273836-11-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Diffstat (limited to 'arch/x86/kvm/pmu.c')
| -rw-r--r-- | arch/x86/kvm/pmu.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c index 8d81f176ab7b..c397b28e3d1b 100644 --- a/arch/x86/kvm/pmu.c +++ b/arch/x86/kvm/pmu.c @@ -838,6 +838,13 @@ static inline bool cpl_is_matched(struct kvm_pmc *pmc) select_user = config & 0x2; } + /* + * Skip the CPL lookup, which isn't free on Intel, if the result will + * be the same regardless of the CPL. + */ + if (select_os == select_user) + return select_os; + return (static_call(kvm_x86_get_cpl)(pmc->vcpu) == 0) ? select_os : select_user; } |