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Re: [Qemu-devel] [PATCH] usb-ehci: Ensure frindex writes leave a valid f
From: |
Alon Levy |
Subject: |
Re: [Qemu-devel] [PATCH] usb-ehci: Ensure frindex writes leave a valid frindex value |
Date: |
Tue, 3 Apr 2012 16:16:02 +0300 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Tue, Apr 03, 2012 at 02:21:47PM +0200, Hans de Goede wrote:
> frindex is a 14 bits counter, so bits 31-14 should always be 0, and
> after the commit titled "usb-ehci: frindex always is a 14 bits counter"
> we rely on frindex always being a multiple of 8. I've not seen this in
> practice, but theoretically a guest can write a value >= 0x4000 or a value
> which is not a multiple of 8 value to frindex, this patch ensures that
> things will still work when that happens.
Acked-by: Alon Levy <address@hidden>
>
> Signed-off-by: Hans de Goede <address@hidden>
> ---
> hw/usb/hcd-ehci.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/hw/usb/hcd-ehci.c b/hw/usb/hcd-ehci.c
> index 64b58e3..8865b4e 100644
> --- a/hw/usb/hcd-ehci.c
> +++ b/hw/usb/hcd-ehci.c
> @@ -1102,6 +1102,10 @@ static void ehci_mem_writel(void *ptr,
> target_phys_addr_t addr, uint32_t val)
> val &= USBINTR_MASK;
> break;
>
> + case FRINDEX:
> + val &= 0x00003ff8; /* frindex is 14bits and always a multiple of 8 */
> + break;
> +
> case CONFIGFLAG:
> val &= 0x1;
> if (val) {
> --
> 1.7.9.3
>
>