Re: [PATCH] iommu/vt-d: Force to flush iotlb before creating superpage

Hi Longpeng,

On 4/1/21 3:18 PM, Longpeng(Mike) wrote:

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c index ee09323..cbcb434 100644 --- a/drivers/iommu/intel/iommu.c +++ b/drivers/iommu/intel/iommu.c @@ -2342,9 +2342,20 @@ static inline int hardware_largepage_caps(struct dmar_domain *domain, * removed to make room for superpage(s). * We're adding new large pages, so make sure * we don't remove their parent tables.

• 		 *
  

• 		 * We also need to flush the iotlb before creating
  

• 		 * superpage to ensure it does not perserves any
  

• 		 * obsolete info.
  	 */
  

• 		dma_pte_free_pagetable(domain, iov_pfn, end_pfn,
  

• 				       largepage_lvl + 1);
  

• 		if (dma_pte_present(pte)) {
  

The dma_pte_free_pagetable() clears a batch of PTEs. So checking current PTE is insufficient. How about removing this check and always performing cache invalidation?

• 			int i;
  

• 			dma_pte_free_pagetable(domain, iov_pfn, end_pfn,
  

• 					       largepage_lvl + 1);
  

• 			for_each_domain_iommu(i, domain)
  

• 				iommu_flush_iotlb_psi(g_iommus[i], domain,
  

• 						      iov_pfn, nr_pages, 0, 0);
  

Best regards, baolu