linux-kernel - Re: [PATCH v4 4/7] iommu/vt-d: Handle non-page aligned address

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Date:   Thu, 16 Jul 2020 09:51:54 +0200
From:   Auger Eric <eric.auger@...hat.com>
To:     Jacob Pan <jacob.jun.pan@...ux.intel.com>,
        iommu@...ts.linux-foundation.org,
        LKML <linux-kernel@...r.kernel.org>,
        Lu Baolu <baolu.lu@...ux.intel.com>,
        Joerg Roedel <joro@...tes.org>,
        David Woodhouse <dwmw2@...radead.org>
Cc:     Yi Liu <yi.l.liu@...el.com>, "Tian, Kevin" <kevin.tian@...el.com>,
        Raj Ashok <ashok.raj@...el.com>
Subject: Re: [PATCH v4 4/7] iommu/vt-d: Handle non-page aligned address

Hi Jacob,

On 7/7/20 2:12 AM, 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.
> 
> Fixes: 61a06a16e36d8 ("iommu/vt-d: Support flushing more translation
> cache types")
> Acked-by: Lu Baolu <baolu.lu@...ux.intel.com>
> Signed-off-by: Liu Yi L <yi.l.liu@...el.com>
> Signed-off-by: Jacob Pan <jacob.jun.pan@...ux.intel.com>
Reviewed-by: Eric Auger <eric.auger@...hat.com>

Thanks

Eric
> 
> ---
>  drivers/iommu/intel/dmar.c | 20 ++++++++++++++++++--
>  1 file changed, 18 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iommu/intel/dmar.c b/drivers/iommu/intel/dmar.c
> index d9f973fa1190..b2c53bada905 100644
> --- a/drivers/iommu/intel/dmar.c
> +++ b/drivers/iommu/intel/dmar.c
> @@ -1455,9 +1455,25 @@ 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 & GENMASK_ULL(size_order + VTD_PAGE_SHIFT, 0))
> +		pr_warn_ratelimited("Invalidate non-aligned address %llx, order %d\n", addr, size_order);
> +
> +	/* Take page address */
> +	desc.qw1 = QI_DEV_EIOTLB_ADDR(addr);
> +
> +	if (size_order) {
> +		/*
> +		 * 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);
>  }
>