The patch below does not apply to the 3.16-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From ef1af2e29622ff3403926ae801a2b10da075a2de Mon Sep 17 00:00:00 2001
From: Paul Mackerras <pau...@samba.org>
Date: Sat, 19 Jul 2014 17:59:35 +1000
Subject: [PATCH] KVM: PPC: Book3S PR: Take SRCU read lock around RTAS
kvm_read_guest() call
This does for PR KVM what c9438092cae4 ("KVM: PPC: Book3S HV: Take SRCU
read lock around kvm_read_guest() call") did for HV KVM, that is,
eliminate a "suspicious rcu_dereference_check() usage!" warning by
taking the SRCU lock around the call to kvmppc_rtas_hcall().
It also fixes a return of RESUME_HOST to return EMULATE_FAIL instead,
since kvmppc_h_pr() is supposed to return EMULATE_* values.
Signed-off-by: Paul Mackerras <pau...@samba.org>
Cc: stable@vger.kernel.org
Signed-off-by: Alexander Graf <ag...@suse.de>
diff --git a/arch/powerpc/kvm/book3s_pr_papr.c
b/arch/powerpc/kvm/book3s_pr_papr.c
index 6d0143fbeb63..ce3c893d509b 100644
--- a/arch/powerpc/kvm/book3s_pr_papr.c
+++ b/arch/powerpc/kvm/book3s_pr_papr.c
@@ -267,6 +267,8 @@ static int kvmppc_h_pr_xics_hcall(struct kvm_vcpu *vcpu,
u32 cmd)
int kvmppc_h_pr(struct kvm_vcpu *vcpu, unsigned long cmd)
{
+ int rc, idx;
+
if (cmd <= MAX_HCALL_OPCODE &&
!test_bit(cmd/4, vcpu->kvm->arch.enabled_hcalls))
return EMULATE_FAIL;
@@ -299,8 +301,11 @@ int kvmppc_h_pr(struct kvm_vcpu *vcpu, unsigned long cmd)
break;
case H_RTAS:
if (list_empty(&vcpu->kvm->arch.rtas_tokens))
- return RESUME_HOST;
- if (kvmppc_rtas_hcall(vcpu))
+ break;
+ idx = srcu_read_lock(&vcpu->kvm->srcu);
+ rc = kvmppc_rtas_hcall(vcpu);
+ srcu_read_unlock(&vcpu->kvm->srcu, idx);
+ if (rc)
break;
kvmppc_set_gpr(vcpu, 3, 0);
return EMULATE_DONE;
--
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