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authorSean Christopherson <sean.j.christopherson@intel.com>2019-04-17 10:15:32 -0700
committerPaolo Bonzini <pbonzini@redhat.com>2019-04-18 18:55:41 +0200
commit39497d7660d9866a47a2dc9055672358da57ad3d (patch)
tree9b102059c8e55d9bfe3bf0fffdb1c300706bddd6 /arch/x86/kvm/x86.h
parent57bf67e73ce9bcce2258890f5abf2adf5f619f1a (diff)
downloadlinux-39497d7660d9866a47a2dc9055672358da57ad3d.tar.bz2
KVM: lapic: Track lapic timer advance per vCPU
Automatically adjusting the globally-shared timer advancement could corrupt the timer, e.g. if multiple vCPUs are concurrently adjusting the advancement value. That could be partially fixed by using a local variable for the arithmetic, but it would still be susceptible to a race when setting timer_advance_adjust_done. And because virtual_tsc_khz and tsc_scaling_ratio are per-vCPU, the correct calibration for a given vCPU may not apply to all vCPUs. Furthermore, lapic_timer_advance_ns is marked __read_mostly, which is effectively violated when finding a stable advancement takes an extended amount of timer. Opportunistically change the definition of lapic_timer_advance_ns to a u32 so that it matches the style of struct kvm_timer. Explicitly pass the param to kvm_create_lapic() so that it doesn't have to be exposed to lapic.c, thus reducing the probability of unintentionally using the global value instead of the per-vCPU value. Cc: Liran Alon <liran.alon@oracle.com> Cc: Wanpeng Li <wanpengli@tencent.com> Reviewed-by: Liran Alon <liran.alon@oracle.com> Cc: stable@vger.kernel.org Fixes: 3b8a5df6c4dc6 ("KVM: LAPIC: Tune lapic_timer_advance_ns automatically") Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/kvm/x86.h')
-rw-r--r--arch/x86/kvm/x86.h2
1 files changed, 0 insertions, 2 deletions
diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index aedc5d0d4989..534d3f28bb01 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -294,8 +294,6 @@ extern u64 kvm_supported_xcr0(void);
extern unsigned int min_timer_period_us;
-extern unsigned int lapic_timer_advance_ns;
-
extern bool enable_vmware_backdoor;
extern struct static_key kvm_no_apic_vcpu;