Jes,
Glad you tracked it down. Can I suggest rather than using memcpy, a
more efficient way might be something like...
#define ZERO_EXTEND(x,bits) ((x) & (~0UL >> (64-(bits))))
*dest = ZERO_EXTEND(p->u.ioreq.data, 8*s);
Matt
On Tue, May 20, 2008 at 11:57:58AM +0200, Jes Sorensen wrote:
> 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
>
> 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@xxxxxxx>
>
> ---
> 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:
--
To unsubscribe from this list: send the line "unsubscribe kvm-ia64" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
