On 2/25/2017 11:10 AM, Borislav Petkov wrote:
On Thu, Feb 16, 2017 at 09:46:04AM -0600, Tom Lendacky wrote:
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@xxxxxxx>
---
Just nitpicks below...
diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c
index ec548e9..a46bcf4 100644
--- a/arch/x86/mm/mem_encrypt.c
+++ b/arch/x86/mm/mem_encrypt.c
@@ -13,11 +13,14 @@
#include <linux/linkage.h>
#include <linux/init.h>
#include <linux/mm.h>
+#include <linux/dma-mapping.h>
+#include <linux/swiotlb.h>
#include <asm/tlbflush.h>
#include <asm/fixmap.h>
#include <asm/setup.h>
#include <asm/bootparam.h>
+#include <asm/cacheflush.h>
extern pmdval_t early_pmd_flags;
int __init __early_make_pgtable(unsigned long, pmdval_t);
@@ -192,3 +195,22 @@ void __init sme_early_init(void)
for (i = 0; i < ARRAY_SIZE(protection_map); i++)
protection_map[i] = pgprot_encrypted(protection_map[i]);
}
+
+/* Architecture __weak replacement functions */
+void __init mem_encrypt_init(void)
+{
+ if (!sme_me_mask)
!sme_active()
no?
I was probably looking ahead to SEV on this one. Basically if the
sme_me_mask is non-zero we will want to make SWIOTLB decrypted.
Unless we're going to be switching SME dynamically at run time?
+ return;
+
+ /* Call into SWIOTLB to update the SWIOTLB DMA buffers */
+ swiotlb_update_mem_attributes();
+}
+
+void swiotlb_set_mem_attributes(void *vaddr, unsigned long size)
+{
+ WARN(PAGE_ALIGN(size) != size,
+ "size is not page aligned (%#lx)\n", size);
"page-aligned" I guess.
Ok.
+
+ /* Make the SWIOTLB buffer area decrypted */
+ set_memory_decrypted((unsigned long)vaddr, size >> PAGE_SHIFT);
+}
diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
index 4ee479f..15e7160 100644
--- a/include/linux/swiotlb.h
+++ b/include/linux/swiotlb.h
@@ -35,6 +35,7 @@ enum swiotlb_force {
extern unsigned long swiotlb_nr_tbl(void);
unsigned long swiotlb_size_or_default(void);
extern int swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs);
+extern void __init swiotlb_update_mem_attributes(void);
/*
* Enumeration for sync targets
diff --git a/init/main.c b/init/main.c
index 8222caa..ba13f8f 100644
--- a/init/main.c
+++ b/init/main.c
@@ -466,6 +466,10 @@ void __init __weak thread_stack_cache_init(void)
}
#endif
+void __init __weak mem_encrypt_init(void)
+{
+}
+
/*
* Set up kernel memory allocators
*/
@@ -614,6 +618,15 @@ asmlinkage __visible void __init start_kernel(void)
*/
locking_selftest();
+ /*
+ * This needs to be called before any devices perform DMA
+ * operations that might use the swiotlb bounce buffers.
SWIOTLB
Ok.
+ * This call will mark the bounce buffers as decrypted so
+ * that their usage will not cause "plain-text" data to be
+ * decrypted when accessed.
+ */
+ mem_encrypt_init();
+
#ifdef CONFIG_BLK_DEV_INITRD
if (initrd_start && !initrd_below_start_ok &&
page_to_pfn(virt_to_page((void *)initrd_start)) < min_low_pfn) {
diff --git a/lib/swiotlb.c b/lib/swiotlb.c
index a8d74a7..c463067 100644
--- a/lib/swiotlb.c
+++ b/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 +156,17 @@ 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 phys_to_dma(hwdev, address) & ~sme_me_mask;
+}
+
/* 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 +195,31 @@ void swiotlb_print_info(void)
bytes >> 20, vstart, vend - 1);
}
+/*
+ * Early SWIOTLB allocation may be to early to allow an architecture to
too
Yup.
+ * perform the desired operations. This function allows the architecture to
+ * call SWIOTLB when the operations are possible. This function needs to be
s/This function/It/
Ok.
Thanks,
Tom
+ * 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;
