From 933fcd01e97e2ba29880dd5f1239365e40094950 Mon Sep 17 00:00:00 2001
From: Lu Baolu <baolu.lu@linux.intel.com>
Date: Thu, 4 Feb 2021 09:43:58 +0800
Subject: [PATCH] iommu/vt-d: Add iotlb_sync_map callback
Some Intel VT-d hardware implementations don't support memory coherency
for page table walk (presented by the Page-Walk-coherency bit in the
ecap register), so that software must flush the corresponding CPU cache
lines explicitly after each page table entry update.
The iommu_map_sg() code iterates through the given scatter-gather list
and invokes iommu_map() for each element in the scatter-gather list,
which calls into the vendor IOMMU driver through iommu_ops callback. As
the result, a single sg mapping may lead to multiple cache line flushes,
which leads to the degradation of I/O performance after the commit
<c588072bba6b5> ("iommu/vt-d: Convert intel iommu driver to the iommu
ops").
Fix this by adding iotlb_sync_map callback and centralizing the clflush
operations after all sg mappings.
Fixes: c588072bba6b5 ("iommu/vt-d: Convert intel iommu driver to the iommu ops")
Reported-by: Chuck Lever <chuck.lever@oracle.com>
Link: https://lore.kernel.org/linux-iommu/D81314ED-5673-44A6-B597-090E3CB83EB0@oracle.com/
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Cc: Robin Murphy <robin.murphy@arm.com>
[ cel: removed @first_pte, which is no longer used ]
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Link: https://lore.kernel.org/linux-iommu/161177763962.1311.15577661784296014186.stgit@manet.1015granger.net
Link: https://lore.kernel.org/r/20210204014401.2846425-5-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
---
drivers/iommu/intel/iommu.c | 90 ++++++++++++++++++++++++-------------
1 file changed, 60 insertions(+), 30 deletions(-)
diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 7dfe681acc3da..761c1b251c1e8 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -2283,9 +2283,9 @@ static int
__domain_mapping(struct dmar_domain *domain, unsigned long iov_pfn,
unsigned long phys_pfn, unsigned long nr_pages, int prot)
{
- struct dma_pte *first_pte = NULL, *pte = NULL;
unsigned int largepage_lvl = 0;
unsigned long lvl_pages = 0;
+ struct dma_pte *pte = NULL;
phys_addr_t pteval;
u64 attr;
@@ -2314,7 +2314,7 @@ __domain_mapping(struct dmar_domain *domain, unsigned long iov_pfn,
largepage_lvl = hardware_largepage_caps(domain, iov_pfn,
phys_pfn, nr_pages);
- first_pte = pte = pfn_to_dma_pte(domain, iov_pfn, &largepage_lvl);
+ pte = pfn_to_dma_pte(domain, iov_pfn, &largepage_lvl);
if (!pte)
return -ENOMEM;
/* It is large page*/
@@ -2375,34 +2375,14 @@ __domain_mapping(struct dmar_domain *domain, unsigned long iov_pfn,
* recalculate 'pte' and switch back to smaller pages for the
* end of the mapping, if the trailing size is not enough to
* use another superpage (i.e. nr_pages < lvl_pages).
+ *
+ * We leave clflush for the leaf pte changes to iotlb_sync_map()
+ * callback.
*/
pte++;
if (!nr_pages || first_pte_in_page(pte) ||
- (largepage_lvl > 1 && nr_pages < lvl_pages)) {
- domain_flush_cache(domain, first_pte,
- (void *)pte - (void *)first_pte);
+ (largepage_lvl > 1 && nr_pages < lvl_pages))
pte = NULL;
- }
- }
-
- return 0;
-}
-
-static int
-domain_mapping(struct dmar_domain *domain, unsigned long iov_pfn,
- unsigned long phys_pfn, unsigned long nr_pages, int prot)
-{
- int iommu_id, ret;
- struct intel_iommu *iommu;
-
- /* Do the real mapping first */
- ret = __domain_mapping(domain, iov_pfn, phys_pfn, nr_pages, prot);
- if (ret)
- return ret;
-
- for_each_domain_iommu(iommu_id, domain) {
- iommu = g_iommus[iommu_id];
- __mapping_notify_one(iommu, domain, iov_pfn, nr_pages);
}
return 0;
@@ -4943,7 +4923,6 @@ static int intel_iommu_map(struct iommu_domain *domain,
struct dmar_domain *dmar_domain = to_dmar_domain(domain);
u64 max_addr;
int prot = 0;
- int ret;
if (iommu_prot & IOMMU_READ)
prot |= DMA_PTE_READ;
@@ -4969,9 +4948,8 @@ static int intel_iommu_map(struct iommu_domain *domain,
/* Round up size to next multiple of PAGE_SIZE, if it and
the low bits of hpa would take us onto the next page */
size = aligned_nrpages(hpa, size);
- ret = domain_mapping(dmar_domain, iova >> VTD_PAGE_SHIFT,
- hpa >> VTD_PAGE_SHIFT, size, prot);
- return ret;
+ return __domain_mapping(dmar_domain, iova >> VTD_PAGE_SHIFT,
+ hpa >> VTD_PAGE_SHIFT, size, prot);
}
static size_t intel_iommu_unmap(struct iommu_domain *domain,
@@ -5424,6 +5402,57 @@ static bool risky_device(struct pci_dev *pdev)
return false;
}
+static void clflush_sync_map(struct dmar_domain *domain, unsigned long clf_pfn,
+ unsigned long clf_pages)
+{
+ struct dma_pte *first_pte = NULL, *pte = NULL;
+ unsigned long lvl_pages = 0;
+ int level = 0;
+
+ while (clf_pages > 0) {
+ if (!pte) {
+ level = 0;
+ pte = pfn_to_dma_pte(domain, clf_pfn, &level);
+ if (WARN_ON(!pte))
+ return;
+ first_pte = pte;
+ lvl_pages = lvl_to_nr_pages(level);
+ }
+
+ if (WARN_ON(!lvl_pages || clf_pages < lvl_pages))
+ return;
+
+ clf_pages -= lvl_pages;
+ clf_pfn += lvl_pages;
+ pte++;
+
+ if (!clf_pages || first_pte_in_page(pte) ||
+ (level > 1 && clf_pages < lvl_pages)) {
+ domain_flush_cache(domain, first_pte,
+ (void *)pte - (void *)first_pte);
+ pte = NULL;
+ }
+ }
+}
+
+static void intel_iommu_iotlb_sync_map(struct iommu_domain *domain,
+ unsigned long iova, size_t size)
+{
+ struct dmar_domain *dmar_domain = to_dmar_domain(domain);
+ unsigned long pages = aligned_nrpages(iova, size);
+ unsigned long pfn = iova >> VTD_PAGE_SHIFT;
+ struct intel_iommu *iommu;
+ int iommu_id;
+
+ if (!dmar_domain->iommu_coherency)
+ clflush_sync_map(dmar_domain, pfn, pages);
+
+ for_each_domain_iommu(iommu_id, dmar_domain) {
+ iommu = g_iommus[iommu_id];
+ __mapping_notify_one(iommu, dmar_domain, pfn, pages);
+ }
+}
+
const struct iommu_ops intel_iommu_ops = {
.capable = intel_iommu_capable,
.domain_alloc = intel_iommu_domain_alloc,
@@ -5436,6 +5465,7 @@ const struct iommu_ops intel_iommu_ops = {
.aux_detach_dev = intel_iommu_aux_detach_device,
.aux_get_pasid = intel_iommu_aux_get_pasid,
.map = intel_iommu_map,
+ .iotlb_sync_map = intel_iommu_iotlb_sync_map,
.unmap = intel_iommu_unmap,
.flush_iotlb_all = intel_flush_iotlb_all,
.iotlb_sync = intel_iommu_tlb_sync,
--
2.30.2