KVM: PPC: Book3S HV: Endian fix for accessing VPA yield count

paulusmack · agraf · commit ecb6d6185b3a · 2015-03-20T11:42:08.000+01:00
The VPA (virtual processor area) is defined by PAPR and is therefore
big-endian, so we need a be32_to_cpu when reading it in
kvmppc_get_yield_count().  Without this, H_CONFER always fails on a
little-endian host, causing SMP guests to waste time spinning on
spinlocks.

Signed-off-by: Paul Mackerras &lt;paulus@samba.org&gt;
Signed-off-by: Alexander Graf &lt;agraf@suse.de&gt;
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
@@ -636,7 +636,7 @@ static int kvmppc_get_yield_count(struct kvm_vcpu *vcpu)
 	spin_lock(&vcpu->arch.vpa_update_lock);
 	lppaca = (struct lppaca *)vcpu->arch.vpa.pinned_addr;
 	if (lppaca)
-		yield_count = lppaca->yield_count;
+		yield_count = be32_to_cpu(lppaca->yield_count);
 	spin_unlock(&vcpu->arch.vpa_update_lock);
 	return yield_count;
 }

Original file line number	Diff line number	Diff line change
`@@ -636,7 +636,7 @@ static int kvmppc_get_yield_count(struct kvm_vcpu *vcpu)`
`636`	`636`	`spin_lock(&vcpu->arch.vpa_update_lock);`
`637`	`637`	`lppaca = (struct lppaca *)vcpu->arch.vpa.pinned_addr;`
`638`	`638`	`if (lppaca)`
`639`		`- yield_count = lppaca->yield_count;`
	`639`	`+ yield_count = be32_to_cpu(lppaca->yield_count);`
`640`	`640`	`spin_unlock(&vcpu->arch.vpa_update_lock);`
`641`	`641`	`return yield_count;`
`642`	`642`	`}`