linux-kernel - [PATCH 4.2 010/258] KVM: PPC: Book3S: Take the kvm->srcu lock in kvmppc_h_logical_ci

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Message-Id: <20151018014730.447278228@linuxfoundation.org>
Date:	Sat, 17 Oct 2015 18:55:23 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Thomas Huth <thuth@...hat.com>,
	Paul Mackerras <paulus@...ba.org>
Subject: [PATCH 4.2 010/258] KVM: PPC: Book3S: Take the kvm->srcu lock in kvmppc_h_logical_ci_load/store()

4.2-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Thomas Huth <thuth@...hat.com>

commit 3eb4ee68254235e4f47bc0410538fcdaede39589 upstream.

Access to the kvm->buses (like with the kvm_io_bus_read() and -write()
functions) has to be protected via the kvm->srcu lock.
The kvmppc_h_logical_ci_load() and -store() functions are missing
this lock so far, so let's add it there, too.
This fixes the problem that the kernel reports "suspicious RCU usage"
when lock debugging is enabled.

Fixes: 99342cf8044420eebdf9297ca03a14cb6a7085a1
Signed-off-by: Thomas Huth <thuth@...hat.com>
Signed-off-by: Paul Mackerras <paulus@...ba.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/powerpc/kvm/book3s.c |    6 ++++++
 1 file changed, 6 insertions(+)

--- a/arch/powerpc/kvm/book3s.c
+++ b/arch/powerpc/kvm/book3s.c
@@ -827,12 +827,15 @@ int kvmppc_h_logical_ci_load(struct kvm_
 	unsigned long size = kvmppc_get_gpr(vcpu, 4);
 	unsigned long addr = kvmppc_get_gpr(vcpu, 5);
 	u64 buf;
+	int srcu_idx;
 	int ret;
 
 	if (!is_power_of_2(size) || (size > sizeof(buf)))
 		return H_TOO_HARD;
 
+	srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
 	ret = kvm_io_bus_read(vcpu, KVM_MMIO_BUS, addr, size, &buf);
+	srcu_read_unlock(&vcpu->kvm->srcu, srcu_idx);
 	if (ret != 0)
 		return H_TOO_HARD;
 
@@ -867,6 +870,7 @@ int kvmppc_h_logical_ci_store(struct kvm
 	unsigned long addr = kvmppc_get_gpr(vcpu, 5);
 	unsigned long val = kvmppc_get_gpr(vcpu, 6);
 	u64 buf;
+	int srcu_idx;
 	int ret;
 
 	switch (size) {
@@ -890,7 +894,9 @@ int kvmppc_h_logical_ci_store(struct kvm
 		return H_TOO_HARD;
 	}
 
+	srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
 	ret = kvm_io_bus_write(vcpu, KVM_MMIO_BUS, addr, size, &buf);
+	srcu_read_unlock(&vcpu->kvm->srcu, srcu_idx);
 	if (ret != 0)
 		return H_TOO_HARD;
 


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