[<prev] [next>] [<thread-prev] [day] [month] [year] [list]
Message-ID: <cdd1c8ff-6bb5-4665-a55a-9d86cd81a8ef@linux.intel.com>
Date: Mon, 1 Sep 2025 15:28:29 +0800
From: Baolu Lu <baolu.lu@...ux.intel.com>
To: Guanghui Feng <guanghuifeng@...ux.alibaba.com>, dwmw2@...radead.org,
joro@...tes.org, will@...nel.org, robin.murphy@....com
Cc: iommu@...ts.linux.dev, linux-kernel@...r.kernel.org,
alikernel-developer@...ux.alibaba.com
Subject: Re: [PATCH] iommu/vt-d: fix iommu pasid memory alloc & max pasid err
On 8/30/25 21:07, Guanghui Feng wrote:
> When intel_pasid_alloc_table allocates memory for Scalable Mode PASID
> directories, the specified memory page order is incorrect, and an
> additional PAGE_SHIFT is added. There is also an error in calculating
> the maximum number of supported PASID directories. In the revised
> implementation, 1 << (order + PASID_PDE_SHIFT - 3) represents the memory
> occupied by the Scalable Mode PASID directory, divided by 8 to represent
> the number of PASID directories, and then multiplied by the number of (1
> << PASID_PDE_SHIFT) entries in each PASID directory.
Do you see any specific issues if the changes described in this patch
are lacking?
>
> Signed-off-by: Guanghui Feng <guanghuifeng@...ux.alibaba.com>
> ---
> drivers/iommu/intel/pasid.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/iommu/intel/pasid.c b/drivers/iommu/intel/pasid.c
> index 52f678975da7..9969913b600b 100644
> --- a/drivers/iommu/intel/pasid.c
> +++ b/drivers/iommu/intel/pasid.c
> @@ -61,14 +61,14 @@ int intel_pasid_alloc_table(struct device *dev)
> size = max_pasid >> (PASID_PDE_SHIFT - 3);
> order = size ? get_order(size) : 0;
> dir = iommu_alloc_pages_node_sz(info->iommu->node, GFP_KERNEL,
> - 1 << (order + PAGE_SHIFT));
> + 1 << order);
This converts the order to the allocation size.
> if (!dir) {
> kfree(pasid_table);
> return -ENOMEM;
> }
>
> pasid_table->table = dir;
> - pasid_table->max_pasid = 1 << (order + PAGE_SHIFT + 3);
With this code, I can get the pasid_table->max_pasid equal to 0x100000
if the device supports PASID, which is what I expect.
> + pasid_table->max_pasid = 1 << (order + PASID_PDE_SHIFT - 3);
> info->pasid_table = pasid_table;
>
> if (!ecap_coherent(info->iommu->ecap))
Thanks,
baolu
Powered by blists - more mailing lists