From: David Gibson <david@gibson.dropbear.id.au>
To: Alexey Kardashevskiy <aik@ozlabs.ru>
Cc: Gavin Shan <gwshan@linux.vnet.ibm.com>,
linux-kernel@vger.kernel.org,
Alex Williamson <alex.williamson@redhat.com>,
Paul Mackerras <paulus@samba.org>,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH kernel v9 18/32] powerpc/iommu/powernv: Release replaced TCE
Date: Thu, 30 Apr 2015 14:21:07 +1000 [thread overview]
Message-ID: <20150430042107.GE15238@voom.redhat.com> (raw)
In-Reply-To: <5540A999.9060507@ozlabs.ru>
[-- Attachment #1: Type: text/plain, Size: 3558 bytes --]
On Wed, Apr 29, 2015 at 07:51:21PM +1000, Alexey Kardashevskiy wrote:
> On 04/29/2015 02:18 PM, David Gibson wrote:
> >On Sat, Apr 25, 2015 at 10:14:42PM +1000, Alexey Kardashevskiy wrote:
> >>At the moment writing new TCE value to the IOMMU table fails with EBUSY
> >>if there is a valid entry already. However PAPR specification allows
> >>the guest to write new TCE value without clearing it first.
> >>
> >>Another problem this patch is addressing is the use of pool locks for
> >>external IOMMU users such as VFIO. The pool locks are to protect
> >>DMA page allocator rather than entries and since the host kernel does
> >>not control what pages are in use, there is no point in pool locks and
> >>exchange()+put_page(oldtce) is sufficient to avoid possible races.
> >>
> >>This adds an exchange() callback to iommu_table_ops which does the same
> >>thing as set() plus it returns replaced TCE and DMA direction so
> >>the caller can release the pages afterwards. The exchange() receives
> >>a physical address unlike set() which receives linear mapping address;
> >>and returns a physical address as the clear() does.
> >>
> >>This implements exchange() for P5IOC2/IODA/IODA2. This adds a requirement
> >>for a platform to have exchange() implemented in order to support VFIO.
> >>
> >>This replaces iommu_tce_build() and iommu_clear_tce() with
> >>a single iommu_tce_xchg().
> >>
> >>This makes sure that TCE permission bits are not set in TCE passed to
> >>IOMMU API as those are to be calculated by platform code from DMA direction.
> >>
> >>This moves SetPageDirty() to the IOMMU code to make it work for both
> >>VFIO ioctl interface in in-kernel TCE acceleration (when it becomes
> >>available later).
> >>
> >>Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
> >>[aw: for the vfio related changes]
> >>Acked-by: Alex Williamson <alex.williamson@redhat.com>
> >
> >This looks mostly good, but there are couple of details that need fixing.
> >
>
>
> [...]
>
> >>diff --git a/arch/powerpc/platforms/powernv/pci.c b/arch/powerpc/platforms/powernv/pci.c
> >>index ba75aa5..e8802ac 100644
> >>--- a/arch/powerpc/platforms/powernv/pci.c
> >>+++ b/arch/powerpc/platforms/powernv/pci.c
> >>@@ -598,6 +598,23 @@ int pnv_tce_build(struct iommu_table *tbl, long index, long npages,
> >> return 0;
> >> }
> >>
> >>+#ifdef CONFIG_IOMMU_API
> >>+int pnv_tce_xchg(struct iommu_table *tbl, long index,
> >>+ unsigned long *tce, enum dma_data_direction *direction)
> >>+{
> >>+ u64 proto_tce = iommu_direction_to_tce_perm(*direction);
> >>+ unsigned long newtce = *tce | proto_tce;
> >>+ unsigned long idx = index - tbl->it_offset;
> >
> >Should this have a BUG_ON or WARN_ON if the supplied tce has bits set
> >below the page mask?
>
>
> Why? The caller checks these bits, do we really need to duplicate it
> here?
Because this is the crunch point where bad bits will actually cause
strange stuff to happen.
As much as anything the point of a BUG_ON would be to document that
this function expects the parameter to be aligned.
>
>
> >>+ *tce = xchg(pnv_tce(tbl, idx), cpu_to_be64(newtce));
> >>+ *tce = be64_to_cpu(*tce);
> >>+ *direction = iommu_tce_direction(*tce);
> >>+ *tce &= ~(TCE_PCI_READ | TCE_PCI_WRITE);
> >>+
> >>+ return 0;
> >>+}
> >>+#endif
>
>
>
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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next prev parent reply other threads:[~2015-04-30 4:37 UTC|newest]
Thread overview: 110+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-25 12:14 [PATCH kernel v9 00/32] powerpc/iommu/vfio: Enable Dynamic DMA windows Alexey Kardashevskiy
2015-04-25 12:14 ` [PATCH kernel v9 01/32] powerpc/iommu: Split iommu_free_table into 2 helpers Alexey Kardashevskiy
2015-04-29 2:03 ` David Gibson
2015-04-25 12:14 ` [PATCH kernel v9 02/32] Revert "powerpc/powernv: Allocate struct pnv_ioda_pe iommu_table dynamically" Alexey Kardashevskiy
2015-04-27 21:05 ` Alex Williamson
2015-04-29 2:05 ` David Gibson
2015-04-25 12:14 ` [PATCH kernel v9 03/32] vfio: powerpc/spapr: Move page pinning from arch code to VFIO IOMMU driver Alexey Kardashevskiy
2015-04-25 12:14 ` [PATCH kernel v9 04/32] vfio: powerpc/spapr: Check that IOMMU page is fully contained by system page Alexey Kardashevskiy
2015-04-25 12:14 ` [PATCH kernel v9 05/32] vfio: powerpc/spapr: Use it_page_size Alexey Kardashevskiy
2015-04-25 12:14 ` [PATCH kernel v9 06/32] vfio: powerpc/spapr: Move locked_vm accounting to helpers Alexey Kardashevskiy
2015-04-25 12:14 ` [PATCH kernel v9 07/32] vfio: powerpc/spapr: Disable DMA mappings on disabled container Alexey Kardashevskiy
2015-04-25 12:14 ` [PATCH kernel v9 08/32] vfio: powerpc/spapr: Moving pinning/unpinning to helpers Alexey Kardashevskiy
2015-04-29 2:14 ` David Gibson
2015-04-25 12:14 ` [PATCH kernel v9 09/32] vfio: powerpc/spapr: Rework groups attaching Alexey Kardashevskiy
2015-04-29 2:16 ` David Gibson
2015-04-30 2:29 ` Alexey Kardashevskiy
2015-04-30 4:05 ` David Gibson
2015-04-25 12:14 ` [PATCH kernel v9 10/32] powerpc/powernv: Do not set "read" flag if direction==DMA_NONE Alexey Kardashevskiy
2015-04-25 12:14 ` [PATCH kernel v9 11/32] powerpc/iommu: Move tce_xxx callbacks from ppc_md to iommu_table Alexey Kardashevskiy
2015-04-25 12:14 ` [PATCH kernel v9 12/32] powerpc/spapr: vfio: Switch from iommu_table to new iommu_table_group Alexey Kardashevskiy
2015-04-29 2:49 ` David Gibson
2015-04-30 2:30 ` Alexey Kardashevskiy
2015-04-25 12:14 ` [PATCH kernel v9 13/32] vfio: powerpc/spapr/iommu/powernv/ioda2: Rework IOMMU ownership control Alexey Kardashevskiy
2015-04-29 3:02 ` David Gibson
2015-04-29 9:19 ` Alexey Kardashevskiy
2015-04-30 4:08 ` David Gibson
2015-04-25 12:14 ` [PATCH kernel v9 14/32] powerpc/iommu: Fix IOMMU ownership control functions Alexey Kardashevskiy
2015-04-29 3:08 ` David Gibson
2015-04-25 12:14 ` [PATCH kernel v9 15/32] powerpc/powernv/ioda/ioda2: Rework TCE invalidation in tce_build()/tce_free() Alexey Kardashevskiy
2015-04-29 3:18 ` David Gibson
2015-04-30 2:58 ` Alexey Kardashevskiy
2015-04-30 4:16 ` David Gibson
2015-04-25 12:14 ` [PATCH kernel v9 16/32] powerpc/powernv/ioda: Move TCE kill register address to PE Alexey Kardashevskiy
2015-04-27 21:05 ` Alex Williamson
2015-04-29 3:25 ` David Gibson
2015-04-29 9:00 ` Alexey Kardashevskiy
2015-04-30 4:18 ` David Gibson
2015-04-25 12:14 ` [PATCH kernel v9 17/32] powerpc/powernv: Implement accessor to TCE entry Alexey Kardashevskiy
2015-04-29 4:04 ` David Gibson
2015-04-29 9:02 ` Alexey Kardashevskiy
2015-04-30 0:13 ` David Gibson
2015-04-25 12:14 ` [PATCH kernel v9 18/32] powerpc/iommu/powernv: Release replaced TCE Alexey Kardashevskiy
2015-04-29 4:18 ` David Gibson
2015-04-29 9:51 ` Alexey Kardashevskiy
2015-04-30 4:21 ` David Gibson [this message]
2015-04-25 12:14 ` [PATCH kernel v9 19/32] powerpc/powernv/ioda2: Rework iommu_table creation Alexey Kardashevskiy
2015-04-29 4:27 ` David Gibson
2015-04-25 12:14 ` [PATCH kernel v9 20/32] powerpc/powernv/ioda2: Introduce pnv_pci_create_table/pnv_pci_free_table Alexey Kardashevskiy
2015-04-29 4:39 ` David Gibson
2015-04-29 9:12 ` Alexey Kardashevskiy
2015-04-30 4:24 ` David Gibson
2015-05-01 10:13 ` Alexey Kardashevskiy
2015-04-25 12:14 ` [PATCH kernel v9 21/32] powerpc/powernv/ioda2: Introduce pnv_pci_ioda2_set_window Alexey Kardashevskiy
2015-04-29 4:45 ` David Gibson
2015-04-29 9:26 ` Alexey Kardashevskiy
2015-04-30 4:32 ` David Gibson
2015-04-25 12:14 ` [PATCH kernel v9 22/32] powerpc/powernv: Implement multilevel TCE tables Alexey Kardashevskiy
2015-04-29 5:04 ` David Gibson
2015-05-01 9:48 ` Alexey Kardashevskiy
2015-05-05 12:05 ` David Gibson
2015-04-25 12:14 ` [PATCH kernel v9 23/32] powerpc/powernv/ioda: Define and implement DMA table/window management callbacks Alexey Kardashevskiy
2015-04-29 5:30 ` David Gibson
2015-04-29 9:44 ` Alexey Kardashevskiy
2015-04-30 4:37 ` David Gibson
2015-04-30 9:56 ` Alexey Kardashevskiy
2015-05-01 3:36 ` David Gibson
2015-04-25 12:14 ` [PATCH kernel v9 24/32] powerpc/powernv/ioda2: Use new helpers to do proper cleanup on PE release Alexey Kardashevskiy
2015-04-25 12:14 ` [PATCH kernel v9 25/32] vfio: powerpc/spapr: powerpc/powernv/ioda2: Rework ownership Alexey Kardashevskiy
2015-04-29 5:39 ` David Gibson
2015-04-25 12:14 ` [PATCH kernel v9 26/32] powerpc/iommu: Add userspace view of TCE table Alexey Kardashevskiy
2015-04-29 6:31 ` David Gibson
2015-05-01 4:01 ` Alexey Kardashevskiy
2015-05-01 4:23 ` David Gibson
2015-05-01 7:12 ` Alexey Kardashevskiy
2015-05-05 12:02 ` David Gibson
2015-05-11 2:11 ` Alexey Kardashevskiy
2015-05-11 4:52 ` Alexey Kardashevskiy
2015-04-25 12:14 ` [PATCH kernel v9 27/32] powerpc/iommu/ioda2: Add get_table_size() to calculate the size of future table Alexey Kardashevskiy
2015-04-29 6:40 ` David Gibson
2015-05-01 4:10 ` Alexey Kardashevskiy
2015-05-01 5:12 ` David Gibson
2015-05-01 6:53 ` Alexey Kardashevskiy
2015-05-05 11:58 ` David Gibson
2015-05-11 2:24 ` Alexey Kardashevskiy
2015-04-25 12:14 ` [PATCH kernel v9 28/32] powerpc/mmu: Add userspace-to-physical addresses translation cache Alexey Kardashevskiy
2015-04-29 7:01 ` David Gibson
2015-05-01 11:26 ` Alexey Kardashevskiy
2015-05-05 12:12 ` David Gibson
2015-04-30 6:34 ` David Gibson
2015-04-30 8:25 ` Paul Mackerras
2015-05-01 3:39 ` David Gibson
2015-04-25 12:14 ` [PATCH kernel v9 29/32] vfio: powerpc/spapr: Register memory and define IOMMU v2 Alexey Kardashevskiy
2015-04-30 6:55 ` David Gibson
2015-05-01 4:35 ` Alexey Kardashevskiy
2015-05-01 5:23 ` David Gibson
2015-05-01 6:27 ` Alexey Kardashevskiy
2015-05-05 11:53 ` David Gibson
2015-04-25 12:14 ` [PATCH kernel v9 30/32] vfio: powerpc/spapr: Use 32bit DMA window properties from table_group Alexey Kardashevskiy
2015-04-27 22:18 ` Alex Williamson
2015-04-30 6:58 ` David Gibson
2015-04-25 12:14 ` [PATCH kernel v9 31/32] vfio: powerpc/spapr: Support multiple groups in one container if possible Alexey Kardashevskiy
2015-04-30 7:22 ` David Gibson
2015-04-30 9:33 ` Alexey Kardashevskiy
2015-05-01 0:46 ` Benjamin Herrenschmidt
2015-05-01 4:44 ` David Gibson
2015-05-01 4:33 ` David Gibson
2015-05-01 6:05 ` Alexey Kardashevskiy
2015-05-05 11:50 ` David Gibson
2015-05-11 2:26 ` Alexey Kardashevskiy
2015-04-25 12:14 ` [PATCH kernel v9 32/32] vfio: powerpc/spapr: Support Dynamic DMA windows Alexey Kardashevskiy
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