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From: Alex Williamson <alex.williamson@redhat.com>
To: Alexey Kardashevskiy <aik@ozlabs.ru>
Cc: linuxppc-dev@lists.ozlabs.org,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH kernel v7 04/31] vfio: powerpc/spapr: Use it_page_size
Date: Wed, 01 Apr 2015 20:50:33 -0600	[thread overview]
Message-ID: <1427943033.5567.329.camel@redhat.com> (raw)
In-Reply-To: <551CA9D7.2060804@ozlabs.ru>

On Thu, 2015-04-02 at 13:30 +1100, Alexey Kardashevskiy wrote:
> On 04/02/2015 08:48 AM, Alex Williamson wrote:
> > On Sat, 2015-03-28 at 01:54 +1100, Alexey Kardashevskiy wrote:
> >> This makes use of the it_page_size from the iommu_table struct
> >> as page size can differ.
> >>
> >> This replaces missing IOMMU_PAGE_SHIFT macro in commented debug code
> >> as recently introduced IOMMU_PAGE_XXX macros do not include
> >> IOMMU_PAGE_SHIFT.
> >>
> >> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
> >> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
> >> ---
> >>   drivers/vfio/vfio_iommu_spapr_tce.c | 26 +++++++++++++-------------
> >>   1 file changed, 13 insertions(+), 13 deletions(-)
> >>
> >> diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c b/drivers/vfio/vfio_iommu_spapr_tce.c
> >> index f835e63..8bbee22 100644
> >> --- a/drivers/vfio/vfio_iommu_spapr_tce.c
> >> +++ b/drivers/vfio/vfio_iommu_spapr_tce.c
> >> @@ -91,7 +91,7 @@ static int tce_iommu_enable(struct tce_container *container)
> >>   	 * enforcing the limit based on the max that the guest can map.
> >>   	 */
> >>   	down_write(&current->mm->mmap_sem);
> >> -	npages = (tbl->it_size << IOMMU_PAGE_SHIFT_4K) >> PAGE_SHIFT;
> >> +	npages = (tbl->it_size << tbl->it_page_shift) >> PAGE_SHIFT;
> >>   	locked = current->mm->locked_vm + npages;
> >>   	lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
> >>   	if (locked > lock_limit && !capable(CAP_IPC_LOCK)) {
> >> @@ -120,7 +120,7 @@ static void tce_iommu_disable(struct tce_container *container)
> >>
> >>   	down_write(&current->mm->mmap_sem);
> >>   	current->mm->locked_vm -= (container->tbl->it_size <<
> >> -			IOMMU_PAGE_SHIFT_4K) >> PAGE_SHIFT;
> >> +			container->tbl->it_page_shift) >> PAGE_SHIFT;
> >>   	up_write(&current->mm->mmap_sem);
> >>   }
> >>
> >> @@ -222,7 +222,7 @@ static long tce_iommu_build(struct tce_container *container,
> >>   					tce, ret);
> >>   			break;
> >>   		}
> >> -		tce += IOMMU_PAGE_SIZE_4K;
> >> +		tce += IOMMU_PAGE_SIZE(tbl);
> >
> >
> > Is PAGE_SIZE ever smaller than IOMMU_PAGE_SIZE(tbl)?  IOW, can the page
> > we got from get_user_pages_fast() ever not completely fill the tce
> > entry?
> 
> 
> Yes. IOMMU_PAGE_SIZE is 4K/64K/16M (16M is with huge pages enabled in QEMU 
> with -mempath), PAGE_SIZE is 4K/64K (normally 64K).

Isn't that a problem then that you're filling the tce with processor
page sizes via get_user_pages_fast(), but incrementing the tce by by
IOMMU page size?  For example, if PAGE_SIZE = 4K and IOMMU_PAGE_SIZE !=
4K have we really pinned all of the memory backed by the tce?  Where do
you make sure the 4K page is really contiguous for the IOMMU page?


  reply	other threads:[~2015-04-02  2:51 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-03-27 14:54 [PATCH kernel v7 00/31] powerpc/iommu/vfio: Enable Dynamic DMA windows Alexey Kardashevskiy
2015-03-27 14:54 ` [PATCH kernel v7 01/31] vfio: powerpc/spapr: Move page pinning from arch code to VFIO IOMMU driver Alexey Kardashevskiy
2015-03-27 14:54 ` [PATCH kernel v7 02/31] vfio: powerpc/spapr: Do cleanup when releasing the group Alexey Kardashevskiy
2015-03-27 14:54 ` [PATCH kernel v7 03/31] vfio: powerpc/spapr: Check that TCE page size is equal to it_page_size Alexey Kardashevskiy
2015-03-27 14:54 ` [PATCH kernel v7 04/31] vfio: powerpc/spapr: Use it_page_size Alexey Kardashevskiy
2015-04-01 21:48   ` Alex Williamson
2015-04-02  2:30     ` Alexey Kardashevskiy
2015-04-02  2:50       ` Alex Williamson [this message]
2015-04-02  3:40         ` Alexey Kardashevskiy
2015-04-02  3:46           ` Alex Williamson
2015-03-27 14:54 ` [PATCH kernel v7 05/31] vfio: powerpc/spapr: Move locked_vm accounting to helpers Alexey Kardashevskiy
2015-03-27 14:54 ` [PATCH kernel v7 06/31] vfio: powerpc/spapr: Disable DMA mappings on disabled container Alexey Kardashevskiy
2015-03-27 14:54 ` [PATCH kernel v7 07/31] vfio: powerpc/spapr: Moving pinning/unpinning to helpers Alexey Kardashevskiy
2015-03-27 14:54 ` [PATCH kernel v7 08/31] vfio: powerpc/spapr: Rework groups attaching Alexey Kardashevskiy
2015-03-27 14:54 ` [PATCH kernel v7 09/31] powerpc/powernv: Do not set "read" flag if direction==DMA_NONE Alexey Kardashevskiy
2015-03-27 14:54 ` [PATCH kernel v7 10/31] powerpc/iommu: Move tce_xxx callbacks from ppc_md to iommu_table Alexey Kardashevskiy
2015-03-27 14:54 ` [PATCH kernel v7 11/31] powerpc/iommu: Introduce iommu_table_alloc() helper Alexey Kardashevskiy
2015-03-27 14:54 ` [PATCH kernel v7 12/31] powerpc/spapr: vfio: Switch from iommu_table to new iommu_table_group Alexey Kardashevskiy
2015-03-31 21:34   ` Alex Williamson
2015-04-01 21:48   ` Alex Williamson
2015-04-02  2:33     ` Alexey Kardashevskiy
2015-04-02  2:51       ` Alex Williamson
2015-03-27 14:54 ` [PATCH kernel v7 13/31] vfio: powerpc/spapr: powerpc/iommu: Rework IOMMU ownership control Alexey Kardashevskiy
2015-03-27 14:54 ` [PATCH kernel v7 14/31] vfio: powerpc/spapr: powerpc/powernv/ioda2: " Alexey Kardashevskiy
2015-03-27 14:54 ` [PATCH kernel v7 15/31] powerpc/iommu: Fix IOMMU ownership control functions Alexey Kardashevskiy
2015-03-27 14:55 ` [PATCH kernel v7 16/31] powerpc/powernv/ioda/ioda2: Rework tce_build()/tce_free() Alexey Kardashevskiy
2015-03-27 14:55 ` [PATCH kernel v7 17/31] powerpc/iommu/powernv: Release replaced TCE Alexey Kardashevskiy
2015-03-27 14:55 ` [PATCH kernel v7 18/31] powerpc/powernv/ioda2: Rework iommu_table creation Alexey Kardashevskiy
2015-03-27 14:55 ` [PATCH kernel v7 19/31] powerpc/powernv/ioda2: Introduce pnv_pci_ioda2_create_table/pnc_pci_free_table Alexey Kardashevskiy
2015-03-27 14:55 ` [PATCH kernel v7 20/31] powerpc/powernv/ioda2: Introduce pnv_pci_ioda2_set_window Alexey Kardashevskiy
2015-03-27 14:55 ` [PATCH kernel v7 21/31] powerpc/iommu: Split iommu_free_table into 2 helpers Alexey Kardashevskiy
2015-03-27 14:55 ` [PATCH kernel v7 22/31] powerpc/powernv: Implement multilevel TCE tables Alexey Kardashevskiy
2015-03-27 14:55 ` [PATCH kernel v7 23/31] powerpc/powernv: Change prototypes to receive iommu Alexey Kardashevskiy
2015-03-27 14:55 ` [PATCH kernel v7 24/31] powerpc/powernv/ioda: Define and implement DMA table/window management callbacks Alexey Kardashevskiy
2015-03-27 14:55 ` [PATCH kernel v7 25/31] vfio: powerpc/spapr: powerpc/powernv/ioda2: Rework ownership Alexey Kardashevskiy
2015-03-27 14:55 ` [PATCH kernel v7 26/31] powerpc/iommu: Add userspace view of TCE table Alexey Kardashevskiy
2015-04-02 20:50   ` Alex Williamson
2015-04-08  3:22     ` Alexey Kardashevskiy
2015-04-08 15:43       ` Alex Williamson
2015-04-09  3:21         ` Alexey Kardashevskiy
2015-04-09  3:46           ` Alex Williamson
2015-03-27 14:55 ` [PATCH kernel v7 27/31] powerpc/iommu/ioda2: Add get_table_size() to calculate the size of fiture table Alexey Kardashevskiy
2015-03-27 14:55 ` [PATCH kernel v7 28/31] powerpc/mmu: Add userspace-to-physical addresses translation cache Alexey Kardashevskiy
2015-04-01 21:48   ` Alex Williamson
2015-04-02  2:35     ` Alexey Kardashevskiy
2015-03-27 14:55 ` [PATCH kernel v7 29/31] vfio: powerpc/spapr: Register memory and define IOMMU v2 Alexey Kardashevskiy
2015-03-27 14:55 ` [PATCH kernel v7 30/31] vfio: powerpc/spapr: Support multiple groups in one container if possible Alexey Kardashevskiy
2015-03-27 14:55 ` [PATCH kernel v7 31/31] vfio: powerpc/spapr: Support Dynamic DMA windows Alexey Kardashevskiy

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