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From: "André Silva" <afscoelho@gmail.com>
To: Peter Maydell <peter.maydell@linaro.org>
Cc: QEMU Developers <qemu-devel@nongnu.org>,
	"Michael S. Tsirkin" <mst@redhat.com>
Subject: Re: [PATCH] virtio: Prevent double swap due to target pre 1.0 VirtIO
Date: Wed, 8 Jan 2020 16:37:27 -0300	[thread overview]
Message-ID: <CAGTcC7yDmpo843uQEQ9=nyqW-wc=XE+dLvqiLmDf6eHuAxeivg@mail.gmail.com> (raw)
In-Reply-To: <CAFEAcA9v-x31y0CraXkfAN3PVQs+Oyo3F+mTA593Duf0t1Wb0A@mail.gmail.com>

Yes, it looks like. virtio_pci_config_read is called via a pointer
from memory_region_read_accessor and memory_region_write_accessor
calls virtio_pci_config_write.
I tested the patch in a linux/ppc64 host with a FreeBSD/ppc64 guest
and VirtIO 0.9 (legacy) driver and from what I saw the config area is
accessed only in these functions.

Thanks!
andré

On Wed, Jan 8, 2020 at 2:51 PM Peter Maydell <peter.maydell@linaro.org> wrote:
>
> On Wed, 8 Jan 2020 at 16:20, Andre Silva <afscoelho@gmail.com> wrote:
> >
> > Remove the bswap function calls after reading and before writing
> > memory bytes in virtio_pci_config_read and virtio_pci_config_write
> > because they are reverting back an already swapped bytes
>
> Is "because we wrote it via virtio_pci_config_write" really
> the only way that the data read by virtio_pci_config_read
> is ever set or updated ?
>
> thanks
> -- PMM


  reply	other threads:[~2020-01-08 19:38 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-08 16:16 [PATCH] virtio: Prevent double swap due to target pre 1.0 VirtIO Andre Silva
2020-01-08 17:51 ` Peter Maydell
2020-01-08 19:37   ` André Silva [this message]
2020-01-09 10:50 ` Michael S. Tsirkin
2020-01-09 12:25   ` André Silva
2020-01-09 12:39     ` Michael S. Tsirkin
2020-01-09 16:06       ` Greg Kurz
2020-01-09 21:18         ` André Silva
2020-01-10  8:55           ` Greg Kurz
2020-01-10 12:00             ` André Silva
2020-01-10 14:50               ` Greg Kurz
2020-01-10 17:09                 ` André Silva
  -- strict thread matches above, loose matches on Subject: below --
2020-01-08 12:56 Andre Silva
2020-01-08 12:56 ` Andre Silva
2020-01-08 15:49   ` no-reply

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