iommu/vt-d: Cleanup after converting to dma-iommu ops

Some cleanups after converting the driver to use dma-iommu ops.
- Remove nobounce option;
- Cleanup and simplify the path in domain mapping.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Tested-by: Logan Gunthorpe <logang@deltatee.com>
Link: https://lore.kernel.org/r/20201124082057.2614359-8-baolu.lu@linux.intel.com
Signed-off-by: Will Deacon <will@kernel.org>

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 526d65d..76b2a20 100644 (file)
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -1883,11 +1883,6 @@
                        Note that using this option lowers the security
                        provided by tboot because it makes the system
                        vulnerable to DMA attacks.
-               nobounce [Default off]
-                       Disable bounce buffer for untrusted devices such as
-                       the Thunderbolt devices. This will treat the untrusted
-                       devices as the trusted ones, hence might expose security
-                       risks of DMA attacks.
 
        intel_idle.max_cstate=  [KNL,HW,ACPI,X86]
                        0       disables intel_idle and fall back on acpi_idle.

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 30f6909..6d519a6 100644 (file)
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -355,7 +355,6 @@ static int dmar_forcedac;
 static int intel_iommu_strict;
 static int intel_iommu_superpage = 1;
 static int iommu_identity_mapping;
-static int intel_no_bounce;
 static int iommu_skip_te_disable;
 
 #define IDENTMAP_GFX           2
@@ -457,9 +456,6 @@ static int __init intel_iommu_setup(char *str)
                } else if (!strncmp(str, "tboot_noforce", 13)) {
                        pr_info("Intel-IOMMU: not forcing on after tboot. This could expose security risk for tboot\n");
                        intel_iommu_tboot_noforce = 1;
-               } else if (!strncmp(str, "nobounce", 8)) {
-                       pr_info("Intel-IOMMU: No bounce buffer. This could expose security risks of DMA attacks\n");
-                       intel_no_bounce = 1;
                }
 
                str += strcspn(str, ",");
@@ -2277,15 +2273,14 @@ static inline int hardware_largepage_caps(struct dmar_domain *domain,
        return level;
 }
 
-static int __domain_mapping(struct dmar_domain *domain, unsigned long iov_pfn,
-                           struct scatterlist *sg, unsigned long phys_pfn,
-                           unsigned long nr_pages, int prot)
+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;
-       phys_addr_t pteval;
-       unsigned long sg_res = 0;
        unsigned int largepage_lvl = 0;
        unsigned long lvl_pages = 0;
+       phys_addr_t pteval;
        u64 attr;
 
        BUG_ON(!domain_pfn_supported(domain, iov_pfn + nr_pages - 1));
@@ -2297,26 +2292,14 @@ static int __domain_mapping(struct dmar_domain *domain, unsigned long iov_pfn,
        if (domain_use_first_level(domain))
                attr |= DMA_FL_PTE_PRESENT | DMA_FL_PTE_XD | DMA_FL_PTE_US;
 
-       if (!sg) {
-               sg_res = nr_pages;
-               pteval = ((phys_addr_t)phys_pfn << VTD_PAGE_SHIFT) | attr;
-       }
+       pteval = ((phys_addr_t)phys_pfn << VTD_PAGE_SHIFT) | attr;
 
        while (nr_pages > 0) {
                uint64_t tmp;
 
-               if (!sg_res) {
-                       unsigned int pgoff = sg->offset & ~PAGE_MASK;
-
-                       sg_res = aligned_nrpages(sg->offset, sg->length);
-                       sg->dma_address = ((dma_addr_t)iov_pfn << VTD_PAGE_SHIFT) + pgoff;
-                       sg->dma_length = sg->length;
-                       pteval = (sg_phys(sg) - pgoff) | attr;
-                       phys_pfn = pteval >> VTD_PAGE_SHIFT;
-               }
-
                if (!pte) {
-                       largepage_lvl = hardware_largepage_caps(domain, iov_pfn, phys_pfn, sg_res);
+                       largepage_lvl = hardware_largepage_caps(domain, iov_pfn,
+                                       phys_pfn, nr_pages);
 
                        first_pte = pte = pfn_to_dma_pte(domain, iov_pfn, &largepage_lvl);
                        if (!pte)
@@ -2328,7 +2311,7 @@ static int __domain_mapping(struct dmar_domain *domain, unsigned long iov_pfn,
                                pteval |= DMA_PTE_LARGE_PAGE;
                                lvl_pages = lvl_to_nr_pages(largepage_lvl);
 
-                               nr_superpages = sg_res / lvl_pages;
+                               nr_superpages = nr_pages / lvl_pages;
                                end_pfn = iov_pfn + nr_superpages * lvl_pages - 1;
 
                                /*
@@ -2362,48 +2345,45 @@ static int __domain_mapping(struct dmar_domain *domain, unsigned long iov_pfn,
                lvl_pages = lvl_to_nr_pages(largepage_lvl);
 
                BUG_ON(nr_pages < lvl_pages);
-               BUG_ON(sg_res < lvl_pages);
 
                nr_pages -= lvl_pages;
                iov_pfn += lvl_pages;
                phys_pfn += lvl_pages;
                pteval += lvl_pages * VTD_PAGE_SIZE;
-               sg_res -= lvl_pages;
 
                /* If the next PTE would be the first in a new page, then we
-                  need to flush the cache on the entries we've just written.
-                  And then we'll need to recalculate 'pte', so clear it and
-                  let it get set again in the if (!pte) block above.
-
-                  If we're done (!nr_pages) we need to flush the cache too.
-
-                  Also if we've been setting superpages, we may need to
-                  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. sg_res < lvl_pages). */
+                * need to flush the cache on the entries we've just written.
+                * And then we'll need to recalculate 'pte', so clear it and
+                * let it get set again in the if (!pte) block above.
+                *
+                * If we're done (!nr_pages) we need to flush the cache too.
+                *
+                * Also if we've been setting superpages, we may need to
+                * 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).
+                */
                pte++;
                if (!nr_pages || first_pte_in_page(pte) ||
-                   (largepage_lvl > 1 && sg_res < lvl_pages)) {
+                   (largepage_lvl > 1 && nr_pages < lvl_pages)) {
                        domain_flush_cache(domain, first_pte,
                                           (void *)pte - (void *)first_pte);
                        pte = NULL;
                }
-
-               if (!sg_res && nr_pages)
-                       sg = sg_next(sg);
        }
+
        return 0;
 }
 
-static int domain_mapping(struct dmar_domain *domain, unsigned long iov_pfn,
-                         struct scatterlist *sg, unsigned long phys_pfn,
-                         unsigned long nr_pages, int prot)
+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, sg, phys_pfn, nr_pages, prot);
+       ret = __domain_mapping(domain, iov_pfn, phys_pfn, nr_pages, prot);
        if (ret)
                return ret;
 
@@ -2415,20 +2395,6 @@ static int domain_mapping(struct dmar_domain *domain, unsigned long iov_pfn,
        return 0;
 }
 
-static inline int domain_sg_mapping(struct dmar_domain *domain, unsigned long iov_pfn,
-                                   struct scatterlist *sg, unsigned long nr_pages,
-                                   int prot)
-{
-       return domain_mapping(domain, iov_pfn, sg, 0, nr_pages, prot);
-}
-
-static inline int domain_pfn_mapping(struct dmar_domain *domain, unsigned long iov_pfn,
-                                    unsigned long phys_pfn, unsigned long nr_pages,
-                                    int prot)
-{
-       return domain_mapping(domain, iov_pfn, NULL, phys_pfn, nr_pages, prot);
-}
-
 static void domain_context_clear_one(struct intel_iommu *iommu, u8 bus, u8 devfn)
 {
        unsigned long flags;
@@ -2688,7 +2654,7 @@ static int iommu_domain_identity_map(struct dmar_domain *domain,
         */
        dma_pte_clear_range(domain, first_vpfn, last_vpfn);
 
-       return __domain_mapping(domain, first_vpfn, NULL,
+       return __domain_mapping(domain, first_vpfn,
                                first_vpfn, last_vpfn - first_vpfn + 1,
                                DMA_PTE_READ|DMA_PTE_WRITE);
 }
@@ -4942,8 +4908,8 @@ 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_pfn_mapping(dmar_domain, iova >> VTD_PAGE_SHIFT,
-                                hpa >> VTD_PAGE_SHIFT, size, prot);
+       ret = domain_mapping(dmar_domain, iova >> VTD_PAGE_SHIFT,
+                            hpa >> VTD_PAGE_SHIFT, size, prot);
        return ret;
 }