From: Jan Beulich <jbeulich@suse.com>
To: Andrew Cooper <Andrew.Cooper3@citrix.com>
Cc: Paul Durrant <paul@xen.org>,
Roger Pau Monne <roger.pau@citrix.com>,
Rahul Singh <Rahul.Singh@arm.com>,
"xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>
Subject: Re: [PATCH v2 1/3] PCI: simplify (and thus correct) pci_get_pdev{,_by_domain}()
Date: Thu, 11 Aug 2022 15:21:31 +0200 [thread overview]
Message-ID: <b4f39c5f-d197-67c5-8781-e22ad0c0d827@suse.com> (raw)
In-Reply-To: <45cf7907-3ff3-49bd-e700-4333c0e45177@citrix.com>
On 11.08.2022 15:11, Andrew Cooper wrote:
> On 11/08/2022 11:51, Jan Beulich wrote:
>> The last "wildcard" use of either function went away with f591755823a7
>> ("IOMMU/PCI: don't let domain cleanup continue when device de-assignment
>> failed"). Don't allow them to be called this way anymore. Besides
>> simplifying the code this also fixes two bugs:
>>
>> 1) When seg != -1, the outer loops should have been terminated after the
>> first iteration, or else a device with the same BDF but on another
>> segment could be found / returned.
>>
>> Reported-by: Rahul Singh <rahul.singh@arm.com>
>>
>> 2) When seg == -1 calling get_pseg() is bogus. The function (taking a
>> u16) would look for segment 0xffff, which might exist. If it exists,
>> we might then find / return a wrong device.
>>
>> In pci_get_pdev_by_domain() also switch from using the per-segment list
>> to using the per-domain one, with the exception of the hardware domain
>> (see the code comment there).
>>
>> While there also constify "pseg" and drop "pdev"'s already previously
>> unnecessary initializer.
>>
>> Signed-off-by: Jan Beulich <jbeulich@suse.com>
>
> Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Thanks.
> I'm not totally convinced that special casing hwdom is right, because
> quarantine devices are domio not hwdom. But I also can't identify a
> case where it's definitely wrong either.
>
>> --- a/xen/include/xen/pci.h
>> +++ b/xen/include/xen/pci.h
>> @@ -177,10 +177,10 @@ int pci_add_device(u16 seg, u8 bus, u8 d
>> int pci_remove_device(u16 seg, u8 bus, u8 devfn);
>> int pci_ro_device(int seg, int bus, int devfn);
>> int pci_hide_device(unsigned int seg, unsigned int bus, unsigned int devfn);
>> -struct pci_dev *pci_get_pdev(int seg, int bus, int devfn);
>> +struct pci_dev *pci_get_pdev(uint16_t seg, uint8_t bus, uint8_t devfn);
>
> I was going to make a request, but I can't quite get it to compile...
>
> Passing sbdf as 3 parameters is a waste, and it would be great if we
> could take this opportunity to improve.
>
> Sadly,
>
> -struct pci_dev *pci_get_pdev(uint16_t seg, uint8_t bus, uint8_t devfn);
> +struct pci_dev *pci_get_pdev(pci_sbdf_t sbdf);
> +
> +#define pci_get_pdev(...) \
> + ({ \
> + count_args(__VA_ARGS__) == 1 \
> + ? pci_get_pdev(__VA_ARGS__) \
> + : pci_get_pdev(PCI_SBDF(__VA_ARGS__)); \
> + })
>
> this doesn't quite compile as a transition plan, and I'm stuck for
> further ideas.
Just look at patch 2.
Jan
next prev parent reply other threads:[~2022-08-11 13:21 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-11 10:50 [PATCH v2 0/3] PCI: re-work pci_get_pdev() and friends Jan Beulich
2022-08-11 10:51 ` [PATCH v2 1/3] PCI: simplify (and thus correct) pci_get_pdev{,_by_domain}() Jan Beulich
2022-08-11 13:11 ` Andrew Cooper
2022-08-11 13:21 ` Jan Beulich [this message]
2022-08-11 16:15 ` Rahul Singh
2022-08-11 10:52 ` [PATCH v2 2/3] PCI: fold pci_get_pdev{,_by_domain}() Jan Beulich
2022-08-11 13:21 ` Andrew Cooper
2022-08-11 13:26 ` Jan Beulich
2022-08-11 15:09 ` Andrew Cooper
2022-08-11 15:41 ` Jan Beulich
2022-08-11 16:17 ` Rahul Singh
2022-08-11 10:52 ` [PATCH v2 3/3] PCI: bring pci_get_real_pdev() in line with pci_get_pdev() Jan Beulich
2022-08-11 13:28 ` Andrew Cooper
2022-08-11 16:16 ` Rahul Singh
2022-08-11 16:37 ` [PATCH] x86/msi: Switch msi_info to using pci_sbdf_t Andrew Cooper
2022-08-12 6:45 ` Jan Beulich
2022-08-12 10:22 ` Andrew Cooper
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