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 14/32] powerpc/iommu: Fix IOMMU ownership control functions
Date: Wed, 29 Apr 2015 13:08:41 +1000 [thread overview]
Message-ID: <20150429030841.GK32589@voom.redhat.com> (raw)
In-Reply-To: <1429964096-11524-15-git-send-email-aik@ozlabs.ru>
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On Sat, Apr 25, 2015 at 10:14:38PM +1000, Alexey Kardashevskiy wrote:
> This adds missing locks in iommu_take_ownership()/
> iommu_release_ownership().
>
> This marks all pages busy in iommu_table::it_map in order to catch
> errors if there is an attempt to use this table while ownership over it
> is taken.
>
> This only clears TCE content if there is no page marked busy in it_map.
> Clearing must be done outside of the table locks as iommu_clear_tce()
> called from iommu_clear_tces_and_put_pages() does this.
>
> In order to use bitmap_empty(), the existing code clears bit#0 which
> is set even in an empty table if it is bus-mapped at 0 as
> iommu_init_table() reserves page#0 to prevent buggy drivers
> from crashing when allocated page is bus-mapped at zero
> (which is correct). This restores the bit in the case of failure
> to bring the it_map to the state it was in when we called
> iommu_take_ownership().
Ah! I finally understand what all this bit#0 stuff is about. Thanks
for the explanation.
>
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
With one small comment..
> ---
> Changes:
> v9:
> * iommu_table_take_ownership() did not return @ret (and ignored EBUSY),
> now it does return correct error.
> * updated commit log about setting bit#0 in the case of failure
>
> v5:
> * do not store bit#0 value, it has to be set for zero-based table
> anyway
> * removed test_and_clear_bit
> ---
> arch/powerpc/kernel/iommu.c | 31 +++++++++++++++++++++++++------
> 1 file changed, 25 insertions(+), 6 deletions(-)
>
> diff --git a/arch/powerpc/kernel/iommu.c b/arch/powerpc/kernel/iommu.c
> index 2856d27..ea2c8ba 100644
> --- a/arch/powerpc/kernel/iommu.c
> +++ b/arch/powerpc/kernel/iommu.c
> @@ -1045,32 +1045,51 @@ EXPORT_SYMBOL_GPL(iommu_tce_build);
>
> int iommu_take_ownership(struct iommu_table *tbl)
> {
> - unsigned long sz = (tbl->it_size + 7) >> 3;
> + unsigned long flags, i, sz = (tbl->it_size + 7) >> 3;
> + int ret = 0;
> +
> + spin_lock_irqsave(&tbl->large_pool.lock, flags);
> + for (i = 0; i < tbl->nr_pools; i++)
> + spin_lock(&tbl->pools[i].lock);
> if (tbl->it_offset == 0)
> clear_bit(0, tbl->it_map);
>
> if (!bitmap_empty(tbl->it_map, tbl->it_size)) {
> pr_err("iommu_tce: it_map is not empty");
> - return -EBUSY;
> + ret = -EBUSY;
> + /* Restore bit#0 set by iommu_init_table() */
> + if (tbl->it_offset == 0)
> + set_bit(0, tbl->it_map);
> + } else {
> + memset(tbl->it_map, 0xff, sz);
> }
>
> - memset(tbl->it_map, 0xff, sz);
> + for (i = 0; i < tbl->nr_pools; i++)
> + spin_unlock(&tbl->pools[i].lock);
I *think* it's safe in this case, but releasing locks not in the
reverse order you acquired them makes me a bit nervous.
> + spin_unlock_irqrestore(&tbl->large_pool.lock, flags);
>
> -
> - return 0;
> + return ret;
> }
> EXPORT_SYMBOL_GPL(iommu_take_ownership);
>
> void iommu_release_ownership(struct iommu_table *tbl)
> {
> - unsigned long sz = (tbl->it_size + 7) >> 3;
> + unsigned long flags, i, sz = (tbl->it_size + 7) >> 3;
> +
> + spin_lock_irqsave(&tbl->large_pool.lock, flags);
> + for (i = 0; i < tbl->nr_pools; i++)
> + spin_lock(&tbl->pools[i].lock);
>
> memset(tbl->it_map, 0, sz);
>
> /* Restore bit#0 set by iommu_init_table() */
> if (tbl->it_offset == 0)
> set_bit(0, tbl->it_map);
> +
> + for (i = 0; i < tbl->nr_pools; i++)
> + spin_unlock(&tbl->pools[i].lock);
> + spin_unlock_irqrestore(&tbl->large_pool.lock, flags);
> }
> EXPORT_SYMBOL_GPL(iommu_release_ownership);
>
--
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:[~2015-04-29 3:26 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 [this message]
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
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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