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author | Ingo Molnar <mingo@kernel.org> | 2015-05-08 13:33:33 +0200 |
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committer | Ingo Molnar <mingo@kernel.org> | 2015-05-08 13:33:33 +0200 |
commit | 7ae383be81781c5e1347f71c3eb0d53ce5188200 (patch) | |
tree | d2dfedb78cf4ee2bc9cc460af3be106b08e01050 /arch/x86/kvm/x86.c | |
parent | 2a4e90b18c256d52a7f3f77d58114f6d4e4a7f9f (diff) | |
parent | 3e0283a53f7d2f2dae7bc4aa7f3104cb5988018f (diff) | |
download | op-kernel-dev-7ae383be81781c5e1347f71c3eb0d53ce5188200.zip op-kernel-dev-7ae383be81781c5e1347f71c3eb0d53ce5188200.tar.gz |
Merge branch 'linus' into x86/asm, before applying dependent patch
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/kvm/x86.c')
-rw-r--r-- | arch/x86/kvm/x86.c | 43 |
1 files changed, 36 insertions, 7 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index e1a8126..c73efcd 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -1669,12 +1669,28 @@ static int kvm_guest_time_update(struct kvm_vcpu *v) &guest_hv_clock, sizeof(guest_hv_clock)))) return 0; - /* - * The interface expects us to write an even number signaling that the - * update is finished. Since the guest won't see the intermediate - * state, we just increase by 2 at the end. + /* This VCPU is paused, but it's legal for a guest to read another + * VCPU's kvmclock, so we really have to follow the specification where + * it says that version is odd if data is being modified, and even after + * it is consistent. + * + * Version field updates must be kept separate. This is because + * kvm_write_guest_cached might use a "rep movs" instruction, and + * writes within a string instruction are weakly ordered. So there + * are three writes overall. + * + * As a small optimization, only write the version field in the first + * and third write. The vcpu->pv_time cache is still valid, because the + * version field is the first in the struct. */ - vcpu->hv_clock.version = guest_hv_clock.version + 2; + BUILD_BUG_ON(offsetof(struct pvclock_vcpu_time_info, version) != 0); + + vcpu->hv_clock.version = guest_hv_clock.version + 1; + kvm_write_guest_cached(v->kvm, &vcpu->pv_time, + &vcpu->hv_clock, + sizeof(vcpu->hv_clock.version)); + + smp_wmb(); /* retain PVCLOCK_GUEST_STOPPED if set in guest copy */ pvclock_flags = (guest_hv_clock.flags & PVCLOCK_GUEST_STOPPED); @@ -1695,6 +1711,13 @@ static int kvm_guest_time_update(struct kvm_vcpu *v) kvm_write_guest_cached(v->kvm, &vcpu->pv_time, &vcpu->hv_clock, sizeof(vcpu->hv_clock)); + + smp_wmb(); + + vcpu->hv_clock.version++; + kvm_write_guest_cached(v->kvm, &vcpu->pv_time, + &vcpu->hv_clock, + sizeof(vcpu->hv_clock.version)); return 0; } @@ -5799,7 +5822,6 @@ int kvm_arch_init(void *opaque) kvm_set_mmio_spte_mask(); kvm_x86_ops = ops; - kvm_init_msr_list(); kvm_mmu_set_mask_ptes(PT_USER_MASK, PT_ACCESSED_MASK, PT_DIRTY_MASK, PT64_NX_MASK, 0); @@ -7253,7 +7275,14 @@ void kvm_arch_hardware_disable(void) int kvm_arch_hardware_setup(void) { - return kvm_x86_ops->hardware_setup(); + int r; + + r = kvm_x86_ops->hardware_setup(); + if (r != 0) + return r; + + kvm_init_msr_list(); + return 0; } void kvm_arch_hardware_unsetup(void) |