[patch] fix zero extending for mmio ld1/2/4 emulation in KVM

[Jes Sorensen <jes@sgi.com>]

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Hi,

This one seems to solve the problem I have been seeing with ld2.acq
not being zero extended under KVM.

I believe this patch is correct - please shoot me if I am wrong.

Cheers,
Jes


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Only copy in the data actually requested by the instruction emulation
and zero pad the destination register first. This avoids the problem
where emulated mmio access got garbled data from ld2.acq instructions
in the vga console driver.

Signed-off-by: Jes Sorensen <jes@sgi.com>

---
 arch/ia64/kvm/mmio.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

Index: linux-2.6.git/arch/ia64/kvm/mmio.c
===================================================================
--- linux-2.6.git.orig/arch/ia64/kvm/mmio.c
+++ linux-2.6.git/arch/ia64/kvm/mmio.c
@@ -158,8 +158,10 @@
 	vmm_transition(vcpu);
 
 	if (p->u.ioreq.state == STATE_IORESP_READY) {
-		if (dir == IOREQ_READ)
-			*dest = p->u.ioreq.data;
+		if (dir == IOREQ_READ) {
+			*dest = 0;
+			memcpy(dest, &p->u.ioreq.data, s);
+		}
 	} else
 		panic_vm(vcpu);
 out: