linux-kernel - Re: [PATCH 4/7] iommu/vt-d: Handle non-page aligned address

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Message-ID: <037cb7cf-1336-f546-7f45-c35caf19930f@linux.intel.com>
Date:   Thu, 25 Jun 2020 18:05:52 +0800
From:   Lu Baolu <baolu.lu@...ux.intel.com>
To:     Jacob Pan <jacob.jun.pan@...ux.intel.com>,
        iommu@...ts.linux-foundation.org,
        LKML <linux-kernel@...r.kernel.org>,
        Joerg Roedel <joro@...tes.org>,
        David Woodhouse <dwmw2@...radead.org>
Cc:     baolu.lu@...ux.intel.com, Yi Liu <yi.l.liu@...el.com>,
        "Tian, Kevin" <kevin.tian@...el.com>,
        Raj Ashok <ashok.raj@...el.com>,
        Eric Auger <eric.auger@...hat.com>
Subject: Re: [PATCH 4/7] iommu/vt-d: Handle non-page aligned address

Hi,

On 2020/6/23 23:43, Jacob Pan wrote:
> From: Liu Yi L <yi.l.liu@...el.com>
> 
> Address information for device TLB invalidation comes from userspace
> when device is directly assigned to a guest with vIOMMU support.
> VT-d requires page aligned address. This patch checks and enforce
> address to be page aligned, otherwise reserved bits can be set in the
> invalidation descriptor. Unrecoverable fault will be reported due to
> non-zero value in the reserved bits.
> 
> Signed-off-by: Liu Yi L <yi.l.liu@...el.com>
> Signed-off-by: Jacob Pan <jacob.jun.pan@...ux.intel.com>
> ---
>   drivers/iommu/intel/dmar.c | 19 +++++++++++++++++--
>   1 file changed, 17 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iommu/intel/dmar.c b/drivers/iommu/intel/dmar.c
> index d9f973fa1190..53f4e5003620 100644
> --- a/drivers/iommu/intel/dmar.c
> +++ b/drivers/iommu/intel/dmar.c
> @@ -1455,9 +1455,24 @@ void qi_flush_dev_iotlb_pasid(struct intel_iommu *iommu, u16 sid, u16 pfsid,
>   	 * Max Invs Pending (MIP) is set to 0 for now until we have DIT in
>   	 * ECAP.
>   	 */
> -	desc.qw1 |= addr & ~mask;
> -	if (size_order)
> +	if (addr & ~VTD_PAGE_MASK)
> +		pr_warn_ratelimited("Invalidate non-page aligned address %llx\n", addr);
> +
> +	if (size_order) {
> +		/* Take page address */
> +		desc.qw1 |= QI_DEV_EIOTLB_ADDR(addr);

If size_order == 0 (that means only a single page is about to be
invalidated), do you still need to set ADDR field of the descriptor?

Best regards,
baolu

> +		/*
> +		 * Existing 0s in address below size_order may be the least
> +		 * significant bit, we must set them to 1s to avoid having
> +		 * smaller size than desired.
> +		 */
> +		desc.qw1 |= GENMASK_ULL(size_order + VTD_PAGE_SHIFT,
> +					VTD_PAGE_SHIFT);
> +		/* Clear size_order bit to indicate size */
> +		desc.qw1 &= ~mask;
> +		/* Set the S bit to indicate flushing more than 1 page */
>   		desc.qw1 |= QI_DEV_EIOTLB_SIZE;
> +	}
>   
>   	qi_submit_sync(iommu, &desc, 1, 0);
>   }
>