[03/10] KVM: PPC: Book3S HV: Fix updates of vcpu->cpu

Submitted by Paul Mackerras on Sept. 21, 2012, 5:35 a.m.

Details

Message ID 20120921053551.GD15685@drongo
State New
Headers show

Commit Message

Paul Mackerras Sept. 21, 2012, 5:35 a.m.
This removes the powerpc "generic" updates of vcpu->cpu in load and
put, and moves them to the various backends.

The reason is that "HV" KVM does its own sauce with that field
and the generic updates might corrupt it. The field contains the
CPU# of the -first- HW CPU of the core always for all the VCPU
threads of a core (the one that's online from a host Linux
perspective).

However, the preempt notifiers are going to be called on the
threads VCPUs when they are running (due to them sleeping on our
private waitqueue) causing unload to be called, potentially
clobbering the value.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
---
 arch/powerpc/kvm/book3s_pr.c |    3 ++-
 arch/powerpc/kvm/booke.c     |    2 ++
 arch/powerpc/kvm/powerpc.c   |    2 --
 3 files changed, 4 insertions(+), 3 deletions(-)

Comments

Alexander Graf Sept. 24, 2012, 12:52 p.m.
On 21.09.2012, at 07:35, Paul Mackerras wrote:

> This removes the powerpc "generic" updates of vcpu->cpu in load and
> put, and moves them to the various backends.
> 
> The reason is that "HV" KVM does its own sauce with that field
> and the generic updates might corrupt it. The field contains the
> CPU# of the -first- HW CPU of the core always for all the VCPU
> threads of a core (the one that's online from a host Linux
> perspective).
> 
> However, the preempt notifiers are going to be called on the
> threads VCPUs when they are running (due to them sleeping on our
> private waitqueue) causing unload to be called, potentially
> clobbering the value.
> 
> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Signed-off-by: Paul Mackerras <paulus@samba.org>

Thanks, applied to kvm-ppc-next.


Alex

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Patch hide | download patch | download mbox

diff --git a/arch/powerpc/kvm/book3s_pr.c b/arch/powerpc/kvm/book3s_pr.c
index 4d0667a..bf3ec5d 100644
--- a/arch/powerpc/kvm/book3s_pr.c
+++ b/arch/powerpc/kvm/book3s_pr.c
@@ -64,7 +64,7 @@  void kvmppc_core_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 	svcpu->slb_max = to_book3s(vcpu)->slb_shadow_max;
 	svcpu_put(svcpu);
 #endif
-
+	vcpu->cpu = smp_processor_id();
 #ifdef CONFIG_PPC_BOOK3S_32
 	current->thread.kvm_shadow_vcpu = to_book3s(vcpu)->shadow_vcpu;
 #endif
@@ -84,6 +84,7 @@  void kvmppc_core_vcpu_put(struct kvm_vcpu *vcpu)
 	kvmppc_giveup_ext(vcpu, MSR_FP);
 	kvmppc_giveup_ext(vcpu, MSR_VEC);
 	kvmppc_giveup_ext(vcpu, MSR_VSX);
+	vcpu->cpu = -1;
 }
 
 int kvmppc_core_check_requests(struct kvm_vcpu *vcpu)
diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
index 3a6490f..69d047c 100644
--- a/arch/powerpc/kvm/booke.c
+++ b/arch/powerpc/kvm/booke.c
@@ -1509,12 +1509,14 @@  void kvmppc_decrementer_func(unsigned long data)
 
 void kvmppc_booke_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 {
+	vcpu->cpu = smp_processor_id();
 	current->thread.kvm_vcpu = vcpu;
 }
 
 void kvmppc_booke_vcpu_put(struct kvm_vcpu *vcpu)
 {
 	current->thread.kvm_vcpu = NULL;
+	vcpu->cpu = -1;
 }
 
 int __init kvmppc_booke_init(void)
diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index 2b08564..fd73763 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -510,7 +510,6 @@  void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 	mtspr(SPRN_VRSAVE, vcpu->arch.vrsave);
 #endif
 	kvmppc_core_vcpu_load(vcpu, cpu);
-	vcpu->cpu = smp_processor_id();
 }
 
 void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
@@ -519,7 +518,6 @@  void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
 #ifdef CONFIG_BOOKE
 	vcpu->arch.vrsave = mfspr(SPRN_VRSAVE);
 #endif
-	vcpu->cpu = -1;
 }
 
 int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,