linux-kernel - Re: [PATCH 6/7] iommu/vt-d: Warn on out-of-range invalidation address

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Message-ID: <d87d15fd-71d5-6735-74df-583024826ab0@linux.intel.com>
Date:   Thu, 25 Jun 2020 18:10:43 +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 6/7] iommu/vt-d: Warn on out-of-range invalidation address

Hi,

On 2020/6/23 23:43, Jacob Pan wrote:
> For guest requested IOTLB invalidation, address and mask are provided as
> part of the invalidation data. VT-d HW silently ignores any address bits
> below the mask. SW shall also allow such case but give warning if
> address does not align with the mask. This patch relax the fault
> handling from error to warning and proceed with invalidation request
> with the given mask.
> 
> Signed-off-by: Jacob Pan <jacob.jun.pan@...ux.intel.com>
> ---
>   drivers/iommu/intel/iommu.c | 7 +++----
>   1 file changed, 3 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
> index 5ea5732d5ec4..50fc62413a35 100644
> --- a/drivers/iommu/intel/iommu.c
> +++ b/drivers/iommu/intel/iommu.c
> @@ -5439,13 +5439,12 @@ intel_iommu_sva_invalidate(struct iommu_domain *domain, struct device *dev,
>   
>   		switch (BIT(cache_type)) {
>   		case IOMMU_CACHE_INV_TYPE_IOTLB:
> +			/* HW will ignore LSB bits based on address mask */
>   			if (inv_info->granularity == IOMMU_INV_GRANU_ADDR &&
>   			    size &&
>   			    (inv_info->addr_info.addr & ((BIT(VTD_PAGE_SHIFT + size)) - 1))) {
> -				pr_err_ratelimited("Address out of range, 0x%llx, size order %llu\n",
> -						   inv_info->addr_info.addr, size);
> -				ret = -ERANGE;
> -				goto out_unlock;
> +				WARN_ONCE(1, "Address out of range, 0x%llx, size order %llu\n",
> +					  inv_info->addr_info.addr, size);

I don't think WARN_ONCE() is suitable here. It makes users think it's a
kernel bug. How about pr_warn_ratelimited()?

Best regards,
baolu

>   			}
>   
>   			/*
>