From: Igor Druzhinin <igor.druzhinin@citrix.com> To: Boris Ostrovsky <boris.ostrovsky@oracle.com>, <xen-devel@lists.xenproject.org>, <linux-kernel@vger.kernel.org> Cc: <jgross@suse.com> Subject: Re: [PATCH] xen/pci: try to reserve MCFG areas earlier Date: Mon, 9 Sep 2019 00:37:12 +0100 [thread overview] Message-ID: <4d3bf854-51de-99e4-9a40-a64c581bdd10@citrix.com> (raw) In-Reply-To: <1695c88d-e5ad-1854-cdef-3cd95c812574@oracle.com> On 09/09/2019 00:30, Boris Ostrovsky wrote: > On 9/8/19 5:11 PM, Igor Druzhinin wrote: >> On 08/09/2019 19:28, Boris Ostrovsky wrote: >>> On 9/6/19 7:00 PM, Igor Druzhinin wrote: >>>> On 06/09/2019 23:30, Boris Ostrovsky wrote: >>>>> Where is MCFG parsed? pci_arch_init()? >>>>>> It happens twice: >>>> 1) first time early one in pci_arch_init() that is arch_initcall - that >>>> time pci_mmcfg_list will be freed immediately there because MCFG area is >>>> not reserved in E820; >>>> 2) second time late one in acpi_init() which is subsystem_initcall right >>>> before where PCI enumeration starts - this time ACPI tables will be >>>> checked for a reserved resource and pci_mmcfg_list will be finally >>>> populated. >>>> >>>> The problem is that on a system that doesn't have MCFG area reserved in >>>> E820 pci_mmcfg_list is empty before acpi_init() and our PCI hooks are >>>> called in the same place. So MCFG is still not in use by Xen at this >>>> point since we haven't reached our xen_mcfg_late(). >>> >>> Would it be possible for us to parse MCFG ourselves in pci_xen_init()? I >>> realize that we'd be doing this twice (or maybe even three times since >>> apparently both pci_arch_init() and acpi_ini() do it). >>> >> I don't thine it makes sense: >> a) it needs to be done after ACPI is initialized since we need to parse >> it to figure out the exact reserved region - that's why it's currently >> done in acpi_init() (see commit message for the reasons why) > > Hmm... We should be able to parse ACPI tables by the time > pci_arch_init() is called. In fact, if you look at > pci_mmcfg_early_init() you will see that it does just that. > The point is not to parse MCFG after acpi_init but to parse DSDT for reserved resource which could be done only after ACPI initialization. >> b) given (a) we cannot do it ourselves before acpi_init and after is too >> late as we're already past ACPI PCI enumeration >> c) we'd have to do it in the same place I call xen_mcfg_late() and it'd >> be code duplication of what's already done by the existing code. > > > If we manage to parse MCFG ourselves early then maybe we won't not need > xen_mcfg_late()? We can call PHYSDEVOP_pci_mmcfg_reserved right away. Again, this cannot be done untile acpi_init finishes basic setup to parse DSDT. Igor
WARNING: multiple messages have this Message-ID (diff)
From: Igor Druzhinin <igor.druzhinin@citrix.com> To: Boris Ostrovsky <boris.ostrovsky@oracle.com>, <xen-devel@lists.xenproject.org>, <linux-kernel@vger.kernel.org> Cc: jgross@suse.com Subject: Re: [Xen-devel] [PATCH] xen/pci: try to reserve MCFG areas earlier Date: Mon, 9 Sep 2019 00:37:12 +0100 [thread overview] Message-ID: <4d3bf854-51de-99e4-9a40-a64c581bdd10@citrix.com> (raw) In-Reply-To: <1695c88d-e5ad-1854-cdef-3cd95c812574@oracle.com> On 09/09/2019 00:30, Boris Ostrovsky wrote: > On 9/8/19 5:11 PM, Igor Druzhinin wrote: >> On 08/09/2019 19:28, Boris Ostrovsky wrote: >>> On 9/6/19 7:00 PM, Igor Druzhinin wrote: >>>> On 06/09/2019 23:30, Boris Ostrovsky wrote: >>>>> Where is MCFG parsed? pci_arch_init()? >>>>>> It happens twice: >>>> 1) first time early one in pci_arch_init() that is arch_initcall - that >>>> time pci_mmcfg_list will be freed immediately there because MCFG area is >>>> not reserved in E820; >>>> 2) second time late one in acpi_init() which is subsystem_initcall right >>>> before where PCI enumeration starts - this time ACPI tables will be >>>> checked for a reserved resource and pci_mmcfg_list will be finally >>>> populated. >>>> >>>> The problem is that on a system that doesn't have MCFG area reserved in >>>> E820 pci_mmcfg_list is empty before acpi_init() and our PCI hooks are >>>> called in the same place. So MCFG is still not in use by Xen at this >>>> point since we haven't reached our xen_mcfg_late(). >>> >>> Would it be possible for us to parse MCFG ourselves in pci_xen_init()? I >>> realize that we'd be doing this twice (or maybe even three times since >>> apparently both pci_arch_init() and acpi_ini() do it). >>> >> I don't thine it makes sense: >> a) it needs to be done after ACPI is initialized since we need to parse >> it to figure out the exact reserved region - that's why it's currently >> done in acpi_init() (see commit message for the reasons why) > > Hmm... We should be able to parse ACPI tables by the time > pci_arch_init() is called. In fact, if you look at > pci_mmcfg_early_init() you will see that it does just that. > The point is not to parse MCFG after acpi_init but to parse DSDT for reserved resource which could be done only after ACPI initialization. >> b) given (a) we cannot do it ourselves before acpi_init and after is too >> late as we're already past ACPI PCI enumeration >> c) we'd have to do it in the same place I call xen_mcfg_late() and it'd >> be code duplication of what's already done by the existing code. > > > If we manage to parse MCFG ourselves early then maybe we won't not need > xen_mcfg_late()? We can call PHYSDEVOP_pci_mmcfg_reserved right away. Again, this cannot be done untile acpi_init finishes basic setup to parse DSDT. Igor _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
next prev parent reply other threads:[~2019-09-08 23:37 UTC|newest] Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-09-04 0:20 [PATCH] xen/pci: try to reserve MCFG areas earlier Igor Druzhinin 2019-09-04 0:20 ` [Xen-devel] " Igor Druzhinin 2019-09-04 9:08 ` Jan Beulich 2019-09-04 9:08 ` [Xen-devel] " Jan Beulich 2019-09-04 11:36 ` Igor Druzhinin 2019-09-04 11:36 ` [Xen-devel] " Igor Druzhinin 2019-09-04 12:09 ` Jan Beulich 2019-09-04 12:09 ` [Xen-devel] " Jan Beulich 2019-09-06 22:30 ` Boris Ostrovsky 2019-09-06 22:30 ` [Xen-devel] " Boris Ostrovsky 2019-09-06 23:00 ` Igor Druzhinin 2019-09-06 23:00 ` [Xen-devel] " Igor Druzhinin 2019-09-08 18:28 ` Boris Ostrovsky 2019-09-08 18:28 ` [Xen-devel] " Boris Ostrovsky 2019-09-08 21:11 ` Igor Druzhinin 2019-09-08 21:11 ` [Xen-devel] " Igor Druzhinin 2019-09-08 23:30 ` Boris Ostrovsky 2019-09-08 23:30 ` [Xen-devel] " Boris Ostrovsky 2019-09-08 23:37 ` Igor Druzhinin [this message] 2019-09-08 23:37 ` Igor Druzhinin 2019-09-09 19:19 ` Boris Ostrovsky 2019-09-09 19:19 ` [Xen-devel] " Boris Ostrovsky 2019-09-09 21:48 ` Igor Druzhinin 2019-09-09 21:48 ` [Xen-devel] " Igor Druzhinin 2019-09-10 1:47 ` Boris Ostrovsky 2019-09-10 1:47 ` Boris Ostrovsky 2019-09-10 9:46 ` Igor Druzhinin 2019-09-10 9:46 ` Igor Druzhinin 2019-09-10 9:55 ` Jan Beulich 2019-09-10 9:55 ` Jan Beulich 2019-09-10 10:08 ` Igor Druzhinin 2019-09-10 10:08 ` Igor Druzhinin 2019-09-10 17:48 ` Boris Ostrovsky 2019-09-10 17:48 ` Boris Ostrovsky 2019-09-10 20:36 ` Igor Druzhinin 2019-09-10 20:36 ` Igor Druzhinin 2019-09-10 21:19 ` Boris Ostrovsky 2019-09-10 21:19 ` Boris Ostrovsky 2019-09-11 1:15 ` Igor Druzhinin 2019-09-11 1:15 ` Igor Druzhinin 2019-09-11 9:13 ` Jan Beulich 2019-09-11 9:13 ` Jan Beulich 2019-09-12 17:33 ` Boris Ostrovsky 2019-09-12 17:33 ` Boris Ostrovsky
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