Minki/linux
1
0
Fork 1
mirror of https://github.com/torvalds/linux.git synced 2024-12-26 04:42:12 +00:00
Code Issues Packages Projects Releases Wiki Activity

KVM: hyperv: fix locking of struct kvm_hv fields

Browse Source 
Introduce a new mutex to avoid an AB-BA deadlock between kvm->lock and
vcpu->mutex.  Protect accesses in kvm_hv_setup_tsc_page too, as suggested
by Roman.

Reported-by: Dmitry Vyukov <dvyukov@google.com>
Reviewed-by: Roman Kagan <rkagan@virtuozzo.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini 2016-12-12 10:12:53 +01:00
parent 83781d180b
commit 3f5ad8be37
4 changed files with 23 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
Documentation/virtual/kvm/locking.txt
View File

@ -13,8 +13,12 @@ The acquisition orders for mutexes are as follows:
- kvm->slots_lock is taken outside kvm->irq_lock, though acquiring
them together is quite rare.
For spinlocks, kvm_lock is taken outside kvm->mmu_lock. Everything
else is a leaf: no other lock is taken inside the critical sections.
On x86, vcpu->mutex is taken outside kvm->arch.hyperv.hv_lock.
For spinlocks, kvm_lock is taken outside kvm->mmu_lock.
Everything else is a leaf: no other lock is taken inside the critical
sections.
2: Exception
------------

1
arch/x86/include/asm/kvm_host.h
View File

@ -704,6 +704,7 @@ struct kvm_apic_map {
/* Hyper-V emulation context */
struct kvm_hv {
struct mutex hv_lock;
u64 hv_guest_os_id;
u64 hv_hypercall;
u64 hv_tsc_page;

24
arch/x86/kvm/hyperv.c
View File

@ -852,6 +852,10 @@ void kvm_hv_setup_tsc_page(struct kvm *kvm,
if (!(hv->hv_tsc_page & HV_X64_MSR_TSC_REFERENCE_ENABLE))
return;
mutex_lock(&kvm->arch.hyperv.hv_lock);
if (!(hv->hv_tsc_page & HV_X64_MSR_TSC_REFERENCE_ENABLE))
goto out_unlock;
gfn = hv->hv_tsc_page >> HV_X64_MSR_TSC_REFERENCE_ADDRESS_SHIFT;
/*
* Because the TSC parameters only vary when there is a
@ -859,7 +863,7 @@ void kvm_hv_setup_tsc_page(struct kvm *kvm,
*/
if (unlikely(kvm_read_guest(kvm, gfn_to_gpa(gfn),
&tsc_seq, sizeof(tsc_seq))))
return;
goto out_unlock;
/*
* While we're computing and writing the parameters, force the
@ -868,15 +872,15 @@ void kvm_hv_setup_tsc_page(struct kvm *kvm,
hv->tsc_ref.tsc_sequence = 0;
if (kvm_write_guest(kvm, gfn_to_gpa(gfn),
&hv->tsc_ref, sizeof(hv->tsc_ref.tsc_sequence)))
return;
goto out_unlock;
if (!compute_tsc_page_parameters(hv_clock, &hv->tsc_ref))
return;
goto out_unlock;
/* Ensure sequence is zero before writing the rest of the struct. */
smp_wmb();
if (kvm_write_guest(kvm, gfn_to_gpa(gfn), &hv->tsc_ref, sizeof(hv->tsc_ref)))
return;
goto out_unlock;
/*
* Now switch to the TSC page mechanism by writing the sequence.
@ -891,6 +895,8 @@ void kvm_hv_setup_tsc_page(struct kvm *kvm,
hv->tsc_ref.tsc_sequence = tsc_seq;
kvm_write_guest(kvm, gfn_to_gpa(gfn),
&hv->tsc_ref, sizeof(hv->tsc_ref.tsc_sequence));
out_unlock:
mutex_unlock(&kvm->arch.hyperv.hv_lock);
}
static int kvm_hv_set_msr_pw(struct kvm_vcpu *vcpu, u32 msr, u64 data,
@ -1142,9 +1148,9 @@ int kvm_hv_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data, bool host)
if (kvm_hv_msr_partition_wide(msr)) {
int r;
mutex_lock(&vcpu->kvm->lock);
mutex_lock(&vcpu->kvm->arch.hyperv.hv_lock);
r = kvm_hv_set_msr_pw(vcpu, msr, data, host);
mutex_unlock(&vcpu->kvm->lock);
mutex_unlock(&vcpu->kvm->arch.hyperv.hv_lock);
return r;
} else
return kvm_hv_set_msr(vcpu, msr, data, host);
@ -1155,9 +1161,9 @@ int kvm_hv_get_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata)
if (kvm_hv_msr_partition_wide(msr)) {
int r;
mutex_lock(&vcpu->kvm->lock);
mutex_lock(&vcpu->kvm->arch.hyperv.hv_lock);
r = kvm_hv_get_msr_pw(vcpu, msr, pdata);
mutex_unlock(&vcpu->kvm->lock);
mutex_unlock(&vcpu->kvm->arch.hyperv.hv_lock);
return r;
} else
return kvm_hv_get_msr(vcpu, msr, pdata);
@ -1165,7 +1171,7 @@ int kvm_hv_get_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata)
bool kvm_hv_hypercall_enabled(struct kvm *kvm)
{
return kvm->arch.hyperv.hv_hypercall & HV_X64_MSR_HYPERCALL_ENABLE;
return READ_ONCE(kvm->arch.hyperv.hv_hypercall) & HV_X64_MSR_HYPERCALL_ENABLE;
}
static void kvm_hv_hypercall_set_result(struct kvm_vcpu *vcpu, u64 result)

1
arch/x86/kvm/x86.c
View File

@ -7881,6 +7881,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
raw_spin_lock_init(&kvm->arch.tsc_write_lock);
mutex_init(&kvm->arch.apic_map_lock);
mutex_init(&kvm->arch.hyperv.hv_lock);
spin_lock_init(&kvm->arch.pvclock_gtod_sync_lock);
kvm->arch.kvmclock_offset = -ktime_get_boot_ns();