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Re: [PATCH for-5.1] xhci: fix valid.max_access_size to access address re
From: |
Philippe Mathieu-Daudé |
Subject: |
Re: [PATCH for-5.1] xhci: fix valid.max_access_size to access address registers |
Date: |
Tue, 21 Jul 2020 11:17:57 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 |
On 7/21/20 10:33 AM, Laurent Vivier wrote:
> QEMU XHCI advertises AC64 (64-bit addressing) but doesn't allow
> 64-bit mode access in "runtime" and "operational" MemoryRegionOps.
>
> Set the max_access_size based on sizeof(dma_addr_t) as AC64 is set.
>
> XHCI specs:
> "If the xHC supports 64-bit addressing (AC64 = ‘1’), then software
> should write 64-bit registers using only Qword accesses. If a
> system is incapable of issuing Qword accesses, then writes to the
> 64-bit address fields shall be performed using 2 Dword accesses;
> low Dword-first, high-Dword second. If the xHC supports 32-bit
> addressing (AC64 = ‘0’), then the high Dword of registers containing
> 64-bit address fields are unused and software should write addresses
> using only Dword accesses"
You only describe the WRITE path. Is the READ path similar?
>
> The problem has been detected with SLOF, as linux kernel always accesses
> registers using 32-bit access even if AC64 is set and revealed by
> 5d971f9e6725 ("memory: Revert "memory: accept mismatching sizes in
> memory_region_access_valid"")
>
> Suggested-by: Alexey Kardashevskiy <aik@au1.ibm.com>
> Signed-off-by: Laurent Vivier <lvivier@redhat.com>
> ---
> hw/usb/hcd-xhci.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/hw/usb/hcd-xhci.c b/hw/usb/hcd-xhci.c
> index b330e36fe6cc..67a18fe2b64c 100644
> --- a/hw/usb/hcd-xhci.c
> +++ b/hw/usb/hcd-xhci.c
> @@ -3184,7 +3184,7 @@ static const MemoryRegionOps xhci_oper_ops = {
> .read = xhci_oper_read,
> .write = xhci_oper_write,
> .valid.min_access_size = 4,
> - .valid.max_access_size = 4,
> + .valid.max_access_size = sizeof(dma_addr_t),
> .endianness = DEVICE_LITTLE_ENDIAN,
> };
>
> @@ -3200,7 +3200,7 @@ static const MemoryRegionOps xhci_runtime_ops = {
> .read = xhci_runtime_read,
> .write = xhci_runtime_write,
> .valid.min_access_size = 4,
> - .valid.max_access_size = 4,
> + .valid.max_access_size = sizeof(dma_addr_t),
> .endianness = DEVICE_LITTLE_ENDIAN,
> };
I wonder if we shouldn't check the access size now, something like:
bool xhci_check_access_size(void *opaque, hwaddr addr,
unsigned size, bool is_write,
MemTxAttrs attrs);
{
XHCIState *xhci = opaque;
/* FIXME only for is_write??? */
return xhci->ac64 || size == 4;
}
And add to both MemoryRegionOps:
.accepts = xhci_check_access_size,