linux-kernel - Re: [PATCH] habanalabs: Fix virtual address access via debugfs for 2MB pages

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Message-ID: <CAFCwf12Ry+tan4Wov-xJqO0aWbapNsB+xcnHs2f-3LuN7fVRKg@mail.gmail.com>
Date:   Tue, 4 Jun 2019 14:00:54 +0300
From:   Oded Gabbay <oded.gabbay@...il.com>
To:     Tomer Tayar <ttayar@...ana.ai>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] habanalabs: Fix virtual address access via debugfs for
 2MB pages

On Mon, Jun 3, 2019 at 2:25 PM Tomer Tayar <ttayar@...ana.ai> wrote:
>
> The debugfs interface for accessing DRAM virtual addresses currently
> uses the 12 LSBs of a virtual address as an offset.
> However, it should use the 20 LSBs in case the device MMU page size is
> 2MB instead of 4KB.
> This patch fixes the offset calculation to be based on the page size.
>
> Signed-off-by: Tomer Tayar <ttayar@...ana.ai>
> ---
>  drivers/misc/habanalabs/debugfs.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/misc/habanalabs/debugfs.c b/drivers/misc/habanalabs/debugfs.c
> index 0ce5621c1324..ba418aaa404c 100644
> --- a/drivers/misc/habanalabs/debugfs.c
> +++ b/drivers/misc/habanalabs/debugfs.c
> @@ -500,6 +500,7 @@ static int device_va_to_pa(struct hl_device *hdev, u64 virt_addr,
>  {
>         struct hl_ctx *ctx = hdev->user_ctx;
>         u64 hop_addr, hop_pte_addr, hop_pte;
> +       u64 offset_mask = HOP4_MASK | OFFSET_MASK;
>         int rc = 0;
>
>         if (!ctx) {
> @@ -542,12 +543,14 @@ static int device_va_to_pa(struct hl_device *hdev, u64 virt_addr,
>                         goto not_mapped;
>                 hop_pte_addr = get_hop4_pte_addr(ctx, hop_addr, virt_addr);
>                 hop_pte = hdev->asic_funcs->read_pte(hdev, hop_pte_addr);
> +
> +               offset_mask = OFFSET_MASK;
>         }
>
>         if (!(hop_pte & PAGE_PRESENT_MASK))
>                 goto not_mapped;
>
> -       *phys_addr = (hop_pte & PTE_PHYS_ADDR_MASK) | (virt_addr & OFFSET_MASK);
> +       *phys_addr = (hop_pte & ~offset_mask) | (virt_addr & offset_mask);
>
>         goto out;
>
> --
> 2.17.1
>
This patch is:
Reviewed-by: Oded Gabbay <oded.gabbay@...il.com>
applied to -fixes