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Re: [PATCH 2/2] x86/vpci: refuse to map BARs at position 0
- To: Jan Beulich <jbeulich@xxxxxxxx>, Roger Pau Monne <roger.pau@xxxxxxxxxx>
- From: Stewart Hildebrand <stewart.hildebrand@xxxxxxx>
- Date: Thu, 22 May 2025 11:44:24 -0400
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- Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxxx>
- Delivery-date: Thu, 22 May 2025 15:44:39 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 5/22/25 10:59, Jan Beulich wrote:
> On 22.05.2025 16:03, Roger Pau Monne wrote:
>> diff --git a/xen/arch/x86/pci.c b/xen/arch/x86/pci.c
>> index 26bb7f6a3c3a..39fd5a16a4aa 100644
>> --- a/xen/arch/x86/pci.c
>> +++ b/xen/arch/x86/pci.c
>> @@ -101,6 +101,15 @@ int pci_conf_write_intercept(unsigned int seg, unsigned
>> int bdf,
>>
>> bool pci_check_bar(const struct pci_dev *pdev, mfn_t start, mfn_t end)
>> {
>> + /*
>> + * Refuse to map BARs at position 0, those are not initialized. This
>> might
>> + * be required by Linux, that can reposition BARs with memory decoding
>> + * enabled. By returning false here bar->enabled will be set to false,
>> and
>> + * bar_write() will work as expected.
>> + */
>> + if ( mfn_eq(start, _mfn(0)) )
>> + return false;
>
> Is this really x86-specific?
No, I think Arm would benefit from this check too. I'm in favor of
moving the check to common.
|
