From a6681bea45b2bc7f1004c5d6efe900457e17ace3 Mon Sep 17 00:00:00 2001 From: Alexander Graf Date: Wed, 31 Jan 2018 22:24:58 +0100 Subject: [PATCH] KVM: PPC: Book3S PR: Fix svcpu copying with preemption enabled commit 07ae5389e98c53bb9e9f308fce9c903bc3ee7720 upstream. When copying between the vcpu and svcpu, we may get scheduled away onto a different host CPU which in turn means our svcpu pointer may change. That means we need to atomically copy to and from the svcpu with preemption disabled, so that all code around it always sees a coherent state. Reported-by: Simon Guo Fixes: 3d3319b45eea ("KVM: PPC: Book3S: PR: Enable interrupts earlier") Signed-off-by: Alexander Graf Signed-off-by: Paul Mackerras Signed-off-by: Ben Hutchings --- arch/powerpc/include/asm/kvm_book3s.h | 6 ++---- arch/powerpc/kvm/book3s_interrupts.S | 4 +--- arch/powerpc/kvm/book3s_pr.c | 20 +++++++++----------- 3 files changed, 12 insertions(+), 18 deletions(-) diff --git a/arch/powerpc/include/asm/kvm_book3s.h b/arch/powerpc/include/asm/kvm_book3s.h index 0689091f9505..15d2307dbdd0 100644 --- a/arch/powerpc/include/asm/kvm_book3s.h +++ b/arch/powerpc/include/asm/kvm_book3s.h @@ -190,10 +190,8 @@ extern void kvmppc_hv_entry_trampoline(void); extern u32 kvmppc_alignment_dsisr(struct kvm_vcpu *vcpu, unsigned int inst); extern ulong kvmppc_alignment_dar(struct kvm_vcpu *vcpu, unsigned int inst); extern int kvmppc_h_pr(struct kvm_vcpu *vcpu, unsigned long cmd); -extern void kvmppc_copy_to_svcpu(struct kvmppc_book3s_shadow_vcpu *svcpu, - struct kvm_vcpu *vcpu); -extern void kvmppc_copy_from_svcpu(struct kvm_vcpu *vcpu, - struct kvmppc_book3s_shadow_vcpu *svcpu); +extern void kvmppc_copy_to_svcpu(struct kvm_vcpu *vcpu); +extern void kvmppc_copy_from_svcpu(struct kvm_vcpu *vcpu); static inline struct kvmppc_vcpu_book3s *to_book3s(struct kvm_vcpu *vcpu) { diff --git a/arch/powerpc/kvm/book3s_interrupts.S b/arch/powerpc/kvm/book3s_interrupts.S index d044b8b7c69d..b053a0b1f853 100644 --- a/arch/powerpc/kvm/book3s_interrupts.S +++ b/arch/powerpc/kvm/book3s_interrupts.S @@ -96,7 +96,7 @@ kvm_start_entry: kvm_start_lightweight: /* Copy registers into shadow vcpu so we can access them in real mode */ - GET_SHADOW_VCPU(r3) + mr r3, r4 bl FUNC(kvmppc_copy_to_svcpu) nop REST_GPR(4, r1) @@ -165,9 +165,7 @@ after_sprg3_load: stw r12, VCPU_TRAP(r3) /* Transfer reg values from shadow vcpu back to vcpu struct */ - /* On 64-bit, interrupts are still off at this point */ - GET_SHADOW_VCPU(r4) bl FUNC(kvmppc_copy_from_svcpu) nop diff --git a/arch/powerpc/kvm/book3s_pr.c b/arch/powerpc/kvm/book3s_pr.c index e587264c2e8c..1d9c536e6b16 100644 --- a/arch/powerpc/kvm/book3s_pr.c +++ b/arch/powerpc/kvm/book3s_pr.c @@ -82,7 +82,7 @@ static void kvmppc_core_vcpu_put_pr(struct kvm_vcpu *vcpu) #ifdef CONFIG_PPC_BOOK3S_64 struct kvmppc_book3s_shadow_vcpu *svcpu = svcpu_get(vcpu); if (svcpu->in_use) { - kvmppc_copy_from_svcpu(vcpu, svcpu); + kvmppc_copy_from_svcpu(vcpu); } memcpy(to_book3s(vcpu)->slb_shadow, svcpu->slb, sizeof(svcpu->slb)); to_book3s(vcpu)->slb_shadow_max = svcpu->slb_max; @@ -95,9 +95,10 @@ static void kvmppc_core_vcpu_put_pr(struct kvm_vcpu *vcpu) } /* Copy data needed by real-mode code from vcpu to shadow vcpu */ -void kvmppc_copy_to_svcpu(struct kvmppc_book3s_shadow_vcpu *svcpu, - struct kvm_vcpu *vcpu) +void kvmppc_copy_to_svcpu(struct kvm_vcpu *vcpu) { + struct kvmppc_book3s_shadow_vcpu *svcpu = svcpu_get(vcpu); + svcpu->gpr[0] = vcpu->arch.gpr[0]; svcpu->gpr[1] = vcpu->arch.gpr[1]; svcpu->gpr[2] = vcpu->arch.gpr[2]; @@ -121,17 +122,14 @@ void kvmppc_copy_to_svcpu(struct kvmppc_book3s_shadow_vcpu *svcpu, svcpu->shadow_fscr = vcpu->arch.shadow_fscr; #endif svcpu->in_use = true; + + svcpu_put(svcpu); } /* Copy data touched by real-mode code from shadow vcpu back to vcpu */ -void kvmppc_copy_from_svcpu(struct kvm_vcpu *vcpu, - struct kvmppc_book3s_shadow_vcpu *svcpu) +void kvmppc_copy_from_svcpu(struct kvm_vcpu *vcpu) { - /* - * vcpu_put would just call us again because in_use hasn't - * been updated yet. - */ - preempt_disable(); + struct kvmppc_book3s_shadow_vcpu *svcpu = svcpu_get(vcpu); /* * Maybe we were already preempted and synced the svcpu from @@ -169,7 +167,7 @@ void kvmppc_copy_from_svcpu(struct kvm_vcpu *vcpu, svcpu->in_use = false; out: - preempt_enable(); + svcpu_put(svcpu); } static int kvmppc_core_check_requests_pr(struct kvm_vcpu *vcpu)