x86, swiotlb: Add memory encryption support

Since DMA addresses will effectively look like 48-bit addresses when the
memory encryption mask is set, SWIOTLB is needed if the DMA mask of the
device performing the DMA does not support 48-bits. SWIOTLB will be
initialized to create decrypted bounce buffers for use by these devices.

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Larry Woodman <lwoodman@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Toshimitsu Kani <toshi.kani@hpe.com>
Cc: kasan-dev@googlegroups.com
Cc: kvm@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Cc: linux-doc@vger.kernel.org
Cc: linux-efi@vger.kernel.org
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/aa2d29b78ae7d508db8881e46a3215231b9327a7.1500319216.git.thomas.lendacky@amd.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

3 files changed, 21 insertions, 7 deletions

diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c
index 5e16d3f29594..0accc2404b92 100644
--- a/arch/x86/kernel/pci-dma.c
+++ b/arch/x86/kernel/pci-dma.c
@@ -93,9 +93,12 @@ again:
 	if (gfpflags_allow_blocking(flag)) {
 		page = dma_alloc_from_contiguous(dev, count, get_order(size),
 						 flag);
-		if (page && page_to_phys(page) + size > dma_mask) {
-			dma_release_from_contiguous(dev, page, count);
-			page = NULL;
+		if (page) {
+			addr = phys_to_dma(dev, page_to_phys(page));
+			if (addr + size > dma_mask) {
+				dma_release_from_contiguous(dev, page, count);
+				page = NULL;
+			}
 		}
 	}
 	/* fallback */
@@ -104,7 +107,7 @@ again:
 	if (!page)
 		return NULL;
 
-	addr = page_to_phys(page);
+	addr = phys_to_dma(dev, page_to_phys(page));
 	if (addr + size > dma_mask) {
 		__free_pages(page, get_order(size));
 
diff --git a/arch/x86/kernel/pci-nommu.c b/arch/x86/kernel/pci-nommu.c
index a6d404087fe3..4fc3cb60ea11 100644
--- a/arch/x86/kernel/pci-nommu.c
+++ b/arch/x86/kernel/pci-nommu.c
@@ -32,7 +32,7 @@ static dma_addr_t nommu_map_page(struct device *dev, struct page *page,
 				 enum dma_data_direction dir,
 				 unsigned long attrs)
 {
-	dma_addr_t bus = page_to_phys(page) + offset;
+	dma_addr_t bus = phys_to_dma(dev, page_to_phys(page)) + offset;
 	WARN_ON(size == 0);
 	if (!check_addr("map_single", dev, bus, size))
 		return NOMMU_MAPPING_ERROR;
diff --git a/arch/x86/kernel/pci-swiotlb.c b/arch/x86/kernel/pci-swiotlb.c
index 1e23577e17cf..677077510e30 100644
--- a/arch/x86/kernel/pci-swiotlb.c
+++ b/arch/x86/kernel/pci-swiotlb.c
@@ -6,12 +6,14 @@
 #include <linux/swiotlb.h>
 #include <linux/bootmem.h>
 #include <linux/dma-mapping.h>
+#include <linux/mem_encrypt.h>
 
 #include <asm/iommu.h>
 #include <asm/swiotlb.h>
 #include <asm/dma.h>
 #include <asm/xen/swiotlb-xen.h>
 #include <asm/iommu_table.h>
+
 int swiotlb __read_mostly;
 
 void *x86_swiotlb_alloc_coherent(struct device *hwdev, size_t size,
@@ -79,8 +81,8 @@ IOMMU_INIT_FINISH(pci_swiotlb_detect_override,
 		  pci_swiotlb_late_init);
 
 /*
- * if 4GB or more detected (and iommu=off not set) return 1
- * and set swiotlb to 1.
+ * If 4GB or more detected (and iommu=off not set) or if SME is active
+ * then set swiotlb to 1 and return 1.
  */
 int __init pci_swiotlb_detect_4gb(void)
 {
@@ -89,6 +91,15 @@ int __init pci_swiotlb_detect_4gb(void)
 	if (!no_iommu && max_possible_pfn > MAX_DMA32_PFN)
 		swiotlb = 1;
 #endif
+
+	/*
+	 * If SME is active then swiotlb will be set to 1 so that bounce
+	 * buffers are allocated and used for devices that do not support
+	 * the addressing range required for the encryption mask.
+	 */
+	if (sme_active())
+		swiotlb = 1;
+
 	return swiotlb;
 }
 IOMMU_INIT(pci_swiotlb_detect_4gb,