From: Alexander Bulekov <alxndr@bu.edu>
To: "Philippe Mathieu-Daudé" <f4bug@amsat.org>
Cc: Thomas Huth <thuth@redhat.com>,
"Michael S. Tsirkin" <mst@redhat.com>,
Richard Henderson <richard.henderson@linaro.org>,
qemu-stable@nongnu.org, qemu-devel@nongnu.org
Subject: Re: [PATCH v2] hw/pci-host/q35: Ignore write of reserved PCIEXBAR LENGTH field
Date: Mon, 21 Jun 2021 10:09:14 -0400 [thread overview]
Message-ID: <20210621140914.a7leozoakgvumalf@mozz.bu.edu> (raw)
In-Reply-To: <20210526142438.281477-1-f4bug@amsat.org>
On 210526 1624, Philippe Mathieu-Daudé wrote:
> libFuzzer triggered the following assertion:
>
> cat << EOF | qemu-system-i386 -M pc-q35-5.0 \
> -nographic -monitor none -serial none \
> -qtest stdio -d guest_errors -trace pci\*
> outl 0xcf8 0xf2000060
> outl 0xcfc 0x8400056e
> EOF
> pci_cfg_write mch 00:0 @0x60 <- 0x8400056e
> Aborted (core dumped)
>
> This is because guest wrote MCH_HOST_BRIDGE_PCIEXBAR_LENGTH_RVD
> (reserved value) to the PCIE XBAR register.
>
> There is no indication on the datasheet about what occurs when
> this value is written. Simply ignore it on QEMU (and report an
> guest error):
>
> pci_cfg_write mch 00:0 @0x60 <- 0x8400056e
> Q35: Reserved PCIEXBAR LENGTH
> pci_cfg_read mch 00:0 @0x0 -> 0x8086
> pci_cfg_read mch 00:0 @0x0 -> 0x29c08086
> ...
>
> Cc: qemu-stable@nongnu.org
> Reported-by: Alexander Bulekov <alxndr@bu.edu>
> BugLink: https://bugs.launchpad.net/qemu/+bug/1878641
> Fixes: df2d8b3ed4 ("q35: Introduce q35 pc based chipset emulator")
> Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
> Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
> ---
Reviewed-by: Alexander Bulekov <alxndr@bu.edu>
prev parent reply other threads:[~2021-06-21 14:12 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-26 14:24 [PATCH v2] hw/pci-host/q35: Ignore write of reserved PCIEXBAR LENGTH field Philippe Mathieu-Daudé
2021-06-14 11:14 ` Philippe Mathieu-Daudé
2021-06-21 10:05 ` Philippe Mathieu-Daudé
2021-06-21 14:09 ` Alexander Bulekov [this message]
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