From: "Burakov, Anatoly" <anatoly.burakov@intel.com>
To: Haiyue Wang <haiyue.wang@intel.com>, dev@dpdk.org
Cc: stable@dpdk.org
Subject: Re: [dpdk-stable] [PATCH v3] bus/pci: fix VF bus error for memory access
Date: Mon, 22 Jun 2020 13:11:48 +0100 [thread overview]
Message-ID: <8a8efd84-5acb-4ad3-dba4-641853730796@intel.com> (raw)
In-Reply-To: <20200622111351.101006-1-haiyue.wang@intel.com>
On 22-Jun-20 12:13 PM, Haiyue Wang wrote:
> To fix CVE-2020-12888, the linux vfio-pci module will invalidate mmaps
> and block MMIO access on disabled memory, it will send a SIGBUS to the
> application:
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=abafbc551fddede3e0a08dee1dcde08fc0eb8476
>
> When the application opens the vfio PCI device, the vfio-pci module will
> enable the bus memory space through PCI read/write access. According to
> the PCIe specification, the 'Memory Space Enable' is always zero for VF:
>
> Table 9-13 Command Register Changes
>
> Bit Location | PF and VF Register Differences | PF | VF
> | From Base | Attributes | Attributes
> -------------+--------------------------------+------------+-----------
> | Memory Space Enable - Does not | |
> | apply to VFs. Must be hardwired| Base | 0b
> 1 | to 0b for VFs. VF Memory Space | |
> | is controlled by the VF MSE bit| |
> | in the VF Control register. | |
> -------------+--------------------------------+------------+-----------
>
> Afterwards the vfio-pci will initialize its own virtual PCI config space
> data ('vconfig') by reading the VF's physical PCI config space, then the
> 'Memory Space Enable' bit in vconfig will always be 0b value. This will
> make the vfio-pci treat the BAR memory space as disabled, and the SIGBUS
> will be triggerred if access these BARs.
>
> By investigation, the VF PCI device *passthrough* into the Guest OS by
> QEMU has the 'Memory Space Enable' with 1b value. That's because every
> PCI driver will start to enable the memory space, and this action will
> be hooked by vfio-pci virtual PCI read/write to set the 'Memory Space
> Enable' in vconfig space to 1b. So VF runs in guest OS has 'Mem+', but
> VF runs in host OS has 'Mem-'.
>
> Align with PCI working mode in Guest/QEMU/Host, in DPDK, enable the PCI
> bus memory space explicitly to avoid access on disabled memory.
>
> Fixes: 33604c31354a ("vfio: refactor PCI BAR mapping")
> Cc: stable@dpdk.org
>
> Signed-off-by: Haiyue Wang <haiyue.wang@intel.com>
> ---
> v3: update the commit log, and fix one debug log with redundant
> description.
> v2: Rewrite the commit log, and put the link into it even it is long.
> ---
Acked-by: Anatoly Burakov <anatoly.burakov@intel.com>
--
Thanks,
Anatoly
next prev parent reply other threads:[~2020-06-22 12:11 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-21 17:40 [dpdk-stable] [PATCH v1] " Haiyue Wang
2020-06-22 6:30 ` [dpdk-stable] [PATCH v2] " Haiyue Wang
2020-06-22 8:52 ` Burakov, Anatoly
2020-06-22 11:25 ` Wang, Haiyue
2020-06-22 11:13 ` [dpdk-stable] [PATCH v3] " Haiyue Wang
2020-06-22 12:11 ` Burakov, Anatoly [this message]
2020-06-23 15:12 ` [dpdk-stable] [dpdk-dev] " Harman Kalra
2020-06-24 20:01 ` David Marchand
2020-06-25 4:01 ` Wang, Haiyue
2020-06-25 3:50 ` [dpdk-stable] [PATCH v4] " Haiyue Wang
2020-06-25 14:09 ` David Marchand
2020-06-25 16:45 ` Kevin Traynor
2020-06-25 18:33 ` Wang, Haiyue
2020-06-26 9:10 ` Kevin Traynor
2020-06-26 9:17 ` David Marchand
2020-06-26 14:14 ` Wang, Haiyue
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