linux-kernel - Re: [PATCH 08/12] iommu/vt-d: Use cache_tag_flush_range() in cache_invalidate

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Message-ID: <d969d4b4-7583-4216-aef5-039c294a5a18@linux.intel.com>
Date: Sun, 7 Apr 2024 15:15:40 +0800
From: Baolu Lu <baolu.lu@...ux.intel.com>
To: "Tian, Kevin" <kevin.tian@...el.com>, Joerg Roedel <joro@...tes.org>,
 Will Deacon <will@...nel.org>, Robin Murphy <robin.murphy@....com>,
 Jason Gunthorpe <jgg@...pe.ca>
Cc: baolu.lu@...ux.intel.com, "Zhang, Tina" <tina.zhang@...el.com>,
 "Liu, Yi L" <yi.l.liu@...el.com>,
 "iommu@...ts.linux.dev" <iommu@...ts.linux.dev>,
 "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 08/12] iommu/vt-d: Use cache_tag_flush_range() in
 cache_invalidate_user

On 3/28/24 3:54 PM, Tian, Kevin wrote:
>> From: Lu Baolu <baolu.lu@...ux.intel.com>
>> Sent: Monday, March 25, 2024 10:17 AM
>>
>> @@ -166,9 +122,9 @@ static int intel_nested_cache_invalidate_user(struct
>> iommu_domain *domain,
>>   			break;
>>   		}
>>
>> -		intel_nested_flush_cache(dmar_domain, inv_entry.addr,
>> -					 inv_entry.npages,
>> -					 inv_entry.flags &
>> IOMMU_VTD_INV_FLAGS_LEAF);
>> +		cache_tag_flush_range(dmar_domain, inv_entry.addr,
>> +				      inv_entry.npages,
>> +				      inv_entry.flags &
>> IOMMU_VTD_INV_FLAGS_LEAF);
> 
> the helper requires an 'end' address but 'npages' is incorrectly used here.

Oh yes! Thanks for pointing this out. I will fix it like below.

diff --git a/drivers/iommu/intel/iommu.h b/drivers/iommu/intel/iommu.h
index c139524274b9..cef997c07158 100644
--- a/drivers/iommu/intel/iommu.h
+++ b/drivers/iommu/intel/iommu.h
@@ -1050,6 +1050,12 @@ static inline unsigned long 
aligned_nrpages(unsigned long host_addr, size_t size
         return PAGE_ALIGN(host_addr + size) >> VTD_PAGE_SHIFT;
  }

+/* Return a size from number of VTD pages. */
+static inline unsigned long nrpages_to_size(unsigned long npages)
+{
+       return npages << VTD_PAGE_SHIFT;
+}
+
  /* Convert value to context PASID directory size field coding. */
  #define context_pdts(pds)      (((pds) & 0x7) << 9)

diff --git a/drivers/iommu/intel/nested.c b/drivers/iommu/intel/nested.c
index e251507cfcc0..ffbd8d98a3b8 100644
--- a/drivers/iommu/intel/nested.c
+++ b/drivers/iommu/intel/nested.c
@@ -123,7 +123,7 @@ static int intel_nested_cache_invalidate_user(struct 
iommu_domain *domain,
                 }

                 cache_tag_flush_range(dmar_domain, inv_entry.addr,
-                                     inv_entry.npages,
+                                     inv_entry.addr + 
nrpages_to_size(inv_entry.npages) - 1,
                                       inv_entry.flags & 
IOMMU_VTD_INV_FLAGS_LEAF);
                 processed++;
         }

Best regards,
baolu