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| author | Yan Zhao <yan.y.zhao@intel.com> | 2024-03-09 02:09:28 +0100 |
|---|---|---|
| committer | Sean Christopherson <seanjc@google.com> | 2024-06-07 16:18:02 +0200 |
| commit | 65a4de0ffd975af7e2ffc9acb875b6a8ae7ee1aa (patch) | |
| tree | fe310365b89d2cc9d4464e40aaad9e12c86c59c1 | |
| parent | srcu: Add an API for a memory barrier after SRCU read lock (diff) | |
| download | linux-65a4de0ffd975af7e2ffc9acb875b6a8ae7ee1aa.tar.xz linux-65a4de0ffd975af7e2ffc9acb875b6a8ae7ee1aa.zip | |
KVM: x86: Ensure a full memory barrier is emitted in the VM-Exit path
Ensure a full memory barrier is emitted in the VM-Exit path, as a full
barrier is required on Intel CPUs to evict WC buffers. This will allow
unconditionally honoring guest PAT on Intel CPUs that support self-snoop.
As srcu_read_lock() is always called in the VM-Exit path and it internally
has a smp_mb(), call smp_mb__after_srcu_read_lock() to avoid adding a
second fence and make sure smp_mb() is called without dependency on
implementation details of srcu_read_lock().
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Yan Zhao <yan.y.zhao@intel.com>
[sean: massage changelog]
Tested-by: Xiangfei Ma <xiangfeix.ma@intel.com>
Tested-by: Yongwei Ma <yongwei.ma@intel.com>
Link: https://lore.kernel.org/r/20240309010929.1403984-5-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
| -rw-r--r-- | arch/x86/kvm/x86.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 869cfaa980bd..121907049190 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -11136,6 +11136,12 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) kvm_vcpu_srcu_read_lock(vcpu); /* + * Call this to ensure WC buffers in guest are evicted after each VM + * Exit, so that the evicted WC writes can be snooped across all cpus + */ + smp_mb__after_srcu_read_lock(); + + /* * Profile KVM exit RIPs: */ if (unlikely(prof_on == KVM_PROFILING)) { |