From: Peter Maydell <peter.maydell@linaro.org>
To: Alexandra Diupina <adiupina@astralinux.ru>
Cc: Alistair Francis <alistair@alistair23.me>,
"Konrad, Frederic" <Frederic.Konrad@amd.com>,
"Edgar E. Iglesias" <edgar.iglesias@gmail.com>,
qemu-arm@nongnu.org, qemu-devel@nongnu.org,
sdl.qemu@linuxtesting.org
Subject: Re: [PATCH v5] xlnx_dpdma: fix descriptor endianness bug
Date: Fri, 3 May 2024 17:43:22 +0100 [thread overview]
Message-ID: <CAFEAcA-jce+fdPeMM4r5148ywxZE-SO1kcub8QaL42WcbafJdA@mail.gmail.com> (raw)
In-Reply-To: <20240502141628.28103-1-adiupina@astralinux.ru>
On Thu, 2 May 2024 at 15:16, Alexandra Diupina <adiupina@astralinux.ru> wrote:
>
> Add xlnx_dpdma_read_descriptor() and
> xlnx_dpdma_write_descriptor() functions.
> xlnx_dpdma_read_descriptor() combines reading a
> descriptor from desc_addr by calling dma_memory_read()
> and swapping the desc fields from guest memory order
> to host memory order. xlnx_dpdma_write_descriptor()
> performs similar actions when writing a descriptor.
>
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
>
> Fixes: d3c6369a96 ("introduce xlnx-dpdma")
> Signed-off-by: Alexandra Diupina <adiupina@astralinux.ru>
> @@ -755,8 +811,10 @@ size_t xlnx_dpdma_start_operation(XlnxDPDMAState *s, uint8_t channel,
> /* The descriptor need to be updated when it's completed. */
> DPRINTF("update the descriptor with the done flag set.\n");
> xlnx_dpdma_desc_set_done(&desc);
> - dma_memory_write(&address_space_memory, desc_addr, &desc,
> - sizeof(DPDMADescriptor), MEMTXATTRS_UNSPECIFIED);
> + if (xlnx_dpdma_write_descriptor(desc_addr, &desc)) {
> + DPRINTF("Can't write the descriptor.\n");
> + break;
> + }
This "break" introduces a behaviour change, so if we want it
it should not be in this patch, which is supposed to just
be fixing the endianness bug. (If we want to try to do the
right thing on write errors here we need to check the device
datasheet to see what it says about the hardware behaviour in
that situation.)
I dropped the "break" line and have queued this to target-arm.next.
thanks
-- PMM
prev parent reply other threads:[~2024-05-03 16:44 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-28 18:11 [PATCH v4] fix endianness bug Alexandra Diupina
2024-04-30 15:00 ` Peter Maydell
2024-04-30 17:08 ` Alex Bennée
2024-05-02 14:16 ` [PATCH v5] xlnx_dpdma: fix descriptor " Alexandra Diupina
2024-05-03 16:43 ` Peter Maydell [this message]
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