From adad0d02a7d3c958121a4eb9d126015a2353db94 Mon Sep 17 00:00:00 2001
From: Colin Ian King <colin.king@canonical.com>
Date: Mon, 19 Sep 2016 07:11:59 +0100
Subject: [PATCH] kvm: svm: fix unsigned compare less than zero comparison
vm_data->avic_vm_id is a u32, so the check for a error
return (less than zero) such as -EAGAIN from
avic_get_next_vm_id currently has no effect whatsoever.
Fix this by using a temporary int for the comparison
and assign vm_data->avic_vm_id to this. I used an explicit
u32 cast in the assignment to show why vm_data->avic_vm_id
cannot be used in the assign/compare steps.
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
arch/x86/kvm/svm.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 8023d5342586c..9b4221471e3d2 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1412,7 +1412,7 @@ static void avic_vm_destroy(struct kvm *kvm)
static int avic_vm_init(struct kvm *kvm)
{
unsigned long flags;
- int err = -ENOMEM;
+ int vm_id, err = -ENOMEM;
struct kvm_arch *vm_data = &kvm->arch;
struct page *p_page;
struct page *l_page;
@@ -1420,9 +1420,10 @@ static int avic_vm_init(struct kvm *kvm)
if (!avic)
return 0;
- vm_data->avic_vm_id = avic_get_next_vm_id();
- if (vm_data->avic_vm_id < 0)
- return vm_data->avic_vm_id;
+ vm_id = avic_get_next_vm_id();
+ if (vm_id < 0)
+ return vm_id;
+ vm_data->avic_vm_id = (u32)vm_id;
/* Allocating physical APIC ID table (4KB) */
p_page = alloc_page(GFP_KERNEL);
--
2.30.2