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Subject[ 056/184] KVM: x86: relax MSR_KVM_SYSTEM_TIME alignment check
2.6.32-longterm review patch.  If anyone has any objections, please let me know.

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

From: Marcelo Tosatti <mtosatti@redhat.com>

RHEL5 i386 guests register non 32-byte aligned addresses:

kvm-clock: cpu 1, msr 0:3018aa5, secondary cpu clock
kvm-clock: cpu 2, msr 0:301f8e9, secondary cpu clock
kvm-clock: cpu 3, msr 0:302672d, secondary cpu clock

Check for an address+len that would cross page boundary
instead.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
[dannf: backported to Debian's 2.6.32]
Signed-off-by: Willy Tarreau <w@1wt.eu>
---
arch/x86/kvm/x86.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index e24e9ce..79905f2 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -925,9 +925,10 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data)
/* ...but clean it before doing the actual write */
vcpu->arch.time_offset = data & ~(PAGE_MASK | 1);

- /* Check that the address is 32-byte aligned. */
- if (vcpu->arch.time_offset &
- (sizeof(struct pvclock_vcpu_time_info) - 1))
+ /* Check that address+len does not cross page boundary */
+ if ((vcpu->arch.time_offset +
+ sizeof(struct pvclock_vcpu_time_info) - 1)
+ & PAGE_MASK)
break;

vcpu->arch.time_page =
--
1.7.12.2.21.g234cd45.dirty




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