From: Lu Baolu <baolu.lu@linux.intel.com>
To: Georgi Djakov <quic_c_gdjako@quicinc.com>,
will@kernel.org, robin.murphy@arm.com
Cc: baolu.lu@linux.intel.com, joro@8bytes.org, isaacm@codeaurora.org,
pratikp@codeaurora.org, iommu@lists.linux-foundation.org,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, djakov@kernel.org
Subject: Re: [PATCH v7 05/15] iommu: Use bitmap to calculate page size in iommu_pgsize()
Date: Thu, 17 Jun 2021 15:16:05 +0800 [thread overview]
Message-ID: <4d28e9cf-ac5d-06db-a110-2cdd3f506924@linux.intel.com> (raw)
In-Reply-To: <1623850736-389584-6-git-send-email-quic_c_gdjako@quicinc.com>
On 6/16/21 9:38 PM, Georgi Djakov wrote:
> From: Will Deacon <will@kernel.org>
>
> Avoid the potential for shifting values by amounts greater than the
> width of their type by using a bitmap to compute page size in
> iommu_pgsize().
>
> Signed-off-by: Will Deacon <will@kernel.org>
> Signed-off-by: Isaac J. Manjarres <isaacm@codeaurora.org>
> Signed-off-by: Georgi Djakov <quic_c_gdjako@quicinc.com>
> ---
> drivers/iommu/iommu.c | 31 ++++++++++++-------------------
> 1 file changed, 12 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index 5419c4b9f27a..80e471ada358 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -8,6 +8,7 @@
>
> #include <linux/device.h>
> #include <linux/kernel.h>
> +#include <linux/bits.h>
> #include <linux/bug.h>
> #include <linux/types.h>
> #include <linux/init.h>
> @@ -2378,30 +2379,22 @@ static size_t iommu_pgsize(struct iommu_domain *domain,
> unsigned long addr_merge, size_t size)
> {
> unsigned int pgsize_idx;
> + unsigned long pgsizes;
> size_t pgsize;
>
> - /* Max page size that still fits into 'size' */
> - pgsize_idx = __fls(size);
> + /* Page sizes supported by the hardware and small enough for @size */
> + pgsizes = domain->pgsize_bitmap & GENMASK(__fls(size), 0);
>
> - /* need to consider alignment requirements ? */
> - if (likely(addr_merge)) {
> - /* Max page size allowed by address */
> - unsigned int align_pgsize_idx = __ffs(addr_merge);
> - pgsize_idx = min(pgsize_idx, align_pgsize_idx);
> - }
> -
> - /* build a mask of acceptable page sizes */
> - pgsize = (1UL << (pgsize_idx + 1)) - 1;
> -
> - /* throw away page sizes not supported by the hardware */
> - pgsize &= domain->pgsize_bitmap;
> + /* Constrain the page sizes further based on the maximum alignment */
> + if (likely(addr_merge))
> + pgsizes &= GENMASK(__ffs(addr_merge), 0);
>
> - /* make sure we're still sane */
> - BUG_ON(!pgsize);
> + /* Make sure we have at least one suitable page size */
> + BUG_ON(!pgsizes);
>
> - /* pick the biggest page */
> - pgsize_idx = __fls(pgsize);
> - pgsize = 1UL << pgsize_idx;
> + /* Pick the biggest page size remaining */
> + pgsize_idx = __fls(pgsizes);
> + pgsize = BIT(pgsize_idx);
>
> return pgsize;
> }
>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Best regards,
baolu
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2021-06-17 7:19 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-16 13:38 [PATCH v7 00/15] Optimizing iommu_[map/unmap] performance Georgi Djakov
2021-06-16 13:38 ` [PATCH v7 01/15] iommu/io-pgtable: Introduce unmap_pages() as a page table op Georgi Djakov
2021-06-16 13:38 ` [PATCH v7 02/15] iommu: Add an unmap_pages() op for IOMMU drivers Georgi Djakov
2021-06-16 13:38 ` [PATCH v7 03/15] iommu/io-pgtable: Introduce map_pages() as a page table op Georgi Djakov
2021-06-16 13:38 ` [PATCH v7 04/15] iommu: Add a map_pages() op for IOMMU drivers Georgi Djakov
2021-06-16 13:38 ` [PATCH v7 05/15] iommu: Use bitmap to calculate page size in iommu_pgsize() Georgi Djakov
2021-06-17 7:16 ` Lu Baolu [this message]
2021-06-16 13:38 ` [PATCH v7 06/15] iommu: Split 'addr_merge' argument to iommu_pgsize() into separate parts Georgi Djakov
2021-06-17 7:17 ` Lu Baolu
2021-06-16 13:38 ` [PATCH v7 07/15] iommu: Hook up '->unmap_pages' driver callback Georgi Djakov
2021-06-17 7:18 ` Lu Baolu
2021-06-16 13:38 ` [PATCH v7 08/15] iommu: Add support for the map_pages() callback Georgi Djakov
2021-06-17 7:18 ` Lu Baolu
2021-06-16 13:38 ` [PATCH v7 09/15] iommu/io-pgtable-arm: Prepare PTE methods for handling multiple entries Georgi Djakov
2021-06-16 13:38 ` [PATCH v7 10/15] iommu/io-pgtable-arm: Implement arm_lpae_unmap_pages() Georgi Djakov
2021-07-15 9:31 ` Kunkun Jiang
2021-06-16 13:38 ` [PATCH v7 11/15] iommu/io-pgtable-arm: Implement arm_lpae_map_pages() Georgi Djakov
2021-06-16 13:38 ` [PATCH v7 12/15] iommu/io-pgtable-arm-v7s: Implement arm_v7s_unmap_pages() Georgi Djakov
2021-06-16 13:38 ` [PATCH v7 13/15] iommu/io-pgtable-arm-v7s: Implement arm_v7s_map_pages() Georgi Djakov
2021-06-16 13:38 ` [PATCH v7 14/15] iommu/arm-smmu: Implement the unmap_pages() IOMMU driver callback Georgi Djakov
2021-06-16 13:38 ` [PATCH v7 15/15] iommu/arm-smmu: Implement the map_pages() " Georgi Djakov
2021-07-14 14:24 ` [PATCH v7 00/15] Optimizing iommu_[map/unmap] performance Georgi Djakov
2021-07-15 1:23 ` Lu Baolu
2021-07-15 1:51 ` chenxiang (M)
2021-07-26 10:37 ` Joerg Roedel
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=4d28e9cf-ac5d-06db-a110-2cdd3f506924@linux.intel.com \
--to=baolu.lu@linux.intel.com \
--cc=djakov@kernel.org \
--cc=iommu@lists.linux-foundation.org \
--cc=isaacm@codeaurora.org \
--cc=joro@8bytes.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=pratikp@codeaurora.org \
--cc=quic_c_gdjako@quicinc.com \
--cc=robin.murphy@arm.com \
--cc=will@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).