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>

lib/swiotlb.c

@@ -30,6 +30,7 @@
 #include <linux/highmem.h>
 #include <linux/gfp.h>
 #include <linux/scatterlist.h>
+#include <linux/mem_encrypt.h>
 
 #include <asm/io.h>
 #include <asm/dma.h>
@@ -155,6 +156,15 @@ unsigned long swiotlb_size_or_default(void)
 	return size ? size : (IO_TLB_DEFAULT_SIZE);
 }
 
+void __weak swiotlb_set_mem_attributes(void *vaddr, unsigned long size) { }
+
+/* For swiotlb, clear memory encryption mask from dma addresses */
+static dma_addr_t swiotlb_phys_to_dma(struct device *hwdev,
+				      phys_addr_t address)
+{
+	return __sme_clr(phys_to_dma(hwdev, address));
+}
+
 /* Note that this doesn't work with highmem page */
 static dma_addr_t swiotlb_virt_to_bus(struct device *hwdev,
 				      volatile void *address)
@@ -183,6 +193,31 @@ void swiotlb_print_info(void)
 	       bytes >> 20, vstart, vend - 1);
 }
 
+/*
+ * Early SWIOTLB allocation may be too early to allow an architecture to
+ * perform the desired operations.  This function allows the architecture to
+ * call SWIOTLB when the operations are possible.  It needs to be called
+ * before the SWIOTLB memory is used.
+ */
+void __init swiotlb_update_mem_attributes(void)
+{
+	void *vaddr;
+	unsigned long bytes;
+
+	if (no_iotlb_memory || late_alloc)
+		return;
+
+	vaddr = phys_to_virt(io_tlb_start);
+	bytes = PAGE_ALIGN(io_tlb_nslabs << IO_TLB_SHIFT);
+	swiotlb_set_mem_attributes(vaddr, bytes);
+	memset(vaddr, 0, bytes);
+
+	vaddr = phys_to_virt(io_tlb_overflow_buffer);
+	bytes = PAGE_ALIGN(io_tlb_overflow);
+	swiotlb_set_mem_attributes(vaddr, bytes);
+	memset(vaddr, 0, bytes);
+}
+
 int __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose)
 {
 	void *v_overflow_buffer;
@@ -320,6 +355,7 @@ swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs)
 	io_tlb_start = virt_to_phys(tlb);
 	io_tlb_end = io_tlb_start + bytes;
 
+	swiotlb_set_mem_attributes(tlb, bytes);
 	memset(tlb, 0, bytes);
 
 	/*
@@ -330,6 +366,8 @@ swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs)
 	if (!v_overflow_buffer)
 		goto cleanup2;
 
+	swiotlb_set_mem_attributes(v_overflow_buffer, io_tlb_overflow);
+	memset(v_overflow_buffer, 0, io_tlb_overflow);
 	io_tlb_overflow_buffer = virt_to_phys(v_overflow_buffer);
 
 	/*
@@ -581,7 +619,7 @@ map_single(struct device *hwdev, phys_addr_t phys, size_t size,
 		return SWIOTLB_MAP_ERROR;
 	}
 
-	start_dma_addr = phys_to_dma(hwdev, io_tlb_start);
+	start_dma_addr = swiotlb_phys_to_dma(hwdev, io_tlb_start);
 	return swiotlb_tbl_map_single(hwdev, start_dma_addr, phys, size,
 				      dir, attrs);
 }
@@ -702,7 +740,7 @@ swiotlb_alloc_coherent(struct device *hwdev, size_t size,
 			goto err_warn;
 
 		ret = phys_to_virt(paddr);
-		dev_addr = phys_to_dma(hwdev, paddr);
+		dev_addr = swiotlb_phys_to_dma(hwdev, paddr);
 
 		/* Confirm address can be DMA'd by device */
 		if (dev_addr + size - 1 > dma_mask) {
@@ -812,10 +850,10 @@ dma_addr_t swiotlb_map_page(struct device *dev, struct page *page,
 	map = map_single(dev, phys, size, dir, attrs);
 	if (map == SWIOTLB_MAP_ERROR) {
 		swiotlb_full(dev, size, dir, 1);
-		return phys_to_dma(dev, io_tlb_overflow_buffer);
+		return swiotlb_phys_to_dma(dev, io_tlb_overflow_buffer);
 	}
 
-	dev_addr = phys_to_dma(dev, map);
+	dev_addr = swiotlb_phys_to_dma(dev, map);
 
 	/* Ensure that the address returned is DMA'ble */
 	if (dma_capable(dev, dev_addr, size))
@@ -824,7 +862,7 @@ dma_addr_t swiotlb_map_page(struct device *dev, struct page *page,
 	attrs |= DMA_ATTR_SKIP_CPU_SYNC;
 	swiotlb_tbl_unmap_single(dev, map, size, dir, attrs);
 
-	return phys_to_dma(dev, io_tlb_overflow_buffer);
+	return swiotlb_phys_to_dma(dev, io_tlb_overflow_buffer);
 }
 EXPORT_SYMBOL_GPL(swiotlb_map_page);
 
@@ -958,7 +996,7 @@ swiotlb_map_sg_attrs(struct device *hwdev, struct scatterlist *sgl, int nelems,
 				sg_dma_len(sgl) = 0;
 				return 0;
 			}
-			sg->dma_address = phys_to_dma(hwdev, map);
+			sg->dma_address = swiotlb_phys_to_dma(hwdev, map);
 		} else
 			sg->dma_address = dev_addr;
 		sg_dma_len(sg) = sg->length;
@@ -1026,7 +1064,7 @@ EXPORT_SYMBOL(swiotlb_sync_sg_for_device);
 int
 swiotlb_dma_mapping_error(struct device *hwdev, dma_addr_t dma_addr)
 {
-	return (dma_addr == phys_to_dma(hwdev, io_tlb_overflow_buffer));
+	return (dma_addr == swiotlb_phys_to_dma(hwdev, io_tlb_overflow_buffer));
 }
 EXPORT_SYMBOL(swiotlb_dma_mapping_error);
 
@@ -1039,6 +1077,6 @@ EXPORT_SYMBOL(swiotlb_dma_mapping_error);
 int
 swiotlb_dma_supported(struct device *hwdev, u64 mask)
 {
-	return phys_to_dma(hwdev, io_tlb_end - 1) <= mask;
+	return swiotlb_phys_to_dma(hwdev, io_tlb_end - 1) <= mask;
 }
 EXPORT_SYMBOL(swiotlb_dma_supported);