If a device doesn't support DMA to a physical address that includes the
encryption bit (currently bit 47, so 48-bit DMA), then the DMA must
occur to unencrypted memory. SWIOTLB is used to satisfy that requirement
if an IOMMU is not active (enabled or configured in passthrough mode).
However, commit
fafadcd16595 ("swiotlb: don't dip into swiotlb pool for
coherent allocations") modified the coherent allocation support in
SWIOTLB to use the DMA direct coherent allocation support. When an IOMMU
is not active, this resulted in dma_alloc_coherent() failing for devices
that didn't support DMA addresses that included the encryption bit.
Addressing this requires changes to the force_dma_unencrypted() function
in kernel/dma/direct.c. Since the function is now non-trivial and
SME/SEV specific, update the DMA direct support to add an arch override
for the force_dma_unencrypted() function. The arch override is selected
when CONFIG_AMD_MEM_ENCRYPT is set. The arch override function resides in
the arch/x86/mm/mem_encrypt.c file and forces unencrypted DMA when either
SEV is active or SME is active and the device does not support DMA to
physical addresses that include the encryption bit.
Fixes:
fafadcd16595 ("swiotlb: don't dip into swiotlb pool for coherent allocations")
Suggested-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
[hch: moved the force_dma_unencrypted declaration to dma-mapping.h,
fold the s390 fix from Halil Pasic]
Signed-off-by: Christoph Hellwig <hch@lst.de>
select VIRT_CPU_ACCOUNTING
select ARCH_HAS_SCALED_CPUTIME
select HAVE_NMI
+ select ARCH_HAS_FORCE_DMA_UNENCRYPTED
select SWIOTLB
select GENERIC_ALLOCATOR
#include <linux/export.h>
#include <linux/cma.h>
#include <linux/gfp.h>
-#include <linux/dma-mapping.h>
+#include <linux/dma-direct.h>
#include <asm/processor.h>
#include <linux/uaccess.h>
#include <asm/pgtable.h>
return is_prot_virt_guest();
}
+bool force_dma_unencrypted(struct device *dev)
+{
+ return sev_active();
+}
+
/* protected virtualization */
static void pv_init(void)
{
depends on X86_64 && CPU_SUP_AMD
select DYNAMIC_PHYSICAL_MASK
select ARCH_USE_MEMREMAP_PROT
+ select ARCH_HAS_FORCE_DMA_UNENCRYPTED
---help---
Say yes to enable support for the encryption of system memory.
This requires an AMD processor that supports Secure Memory
#include <linux/dma-direct.h>
#include <linux/swiotlb.h>
#include <linux/mem_encrypt.h>
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/bitops.h>
+#include <linux/dma-mapping.h>
#include <asm/tlbflush.h>
#include <asm/fixmap.h>
}
EXPORT_SYMBOL(sev_active);
+/* Override for DMA direct allocation check - ARCH_HAS_FORCE_DMA_UNENCRYPTED */
+bool force_dma_unencrypted(struct device *dev)
+{
+ /*
+ * For SEV, all DMA must be to unencrypted addresses.
+ */
+ if (sev_active())
+ return true;
+
+ /*
+ * For SME, all DMA must be to unencrypted addresses if the
+ * device does not support DMA to addresses that include the
+ * encryption mask.
+ */
+ if (sme_active()) {
+ u64 dma_enc_mask = DMA_BIT_MASK(__ffs64(sme_me_mask));
+ u64 dma_dev_mask = min_not_zero(dev->coherent_dma_mask,
+ dev->bus_dma_mask);
+
+ if (dma_dev_mask <= dma_enc_mask)
+ return true;
+ }
+
+ return false;
+}
+
/* Architecture __weak replacement functions */
void __init mem_encrypt_free_decrypted_mem(void)
{
}
#endif /* !CONFIG_ARCH_HAS_PHYS_TO_DMA */
+#ifdef CONFIG_ARCH_HAS_FORCE_DMA_UNENCRYPTED
+bool force_dma_unencrypted(struct device *dev);
+#else
+static inline bool force_dma_unencrypted(struct device *dev)
+{
+ return false;
+}
+#endif /* CONFIG_ARCH_HAS_FORCE_DMA_UNENCRYPTED */
+
/*
* If memory encryption is supported, phys_to_dma will set the memory encryption
* bit in the DMA address, and dma_to_phys will clear it. The raw __phys_to_dma
config ARCH_HAS_DMA_MMAP_PGPROT
bool
+config ARCH_HAS_FORCE_DMA_UNENCRYPTED
+ bool
+
config DMA_NONCOHERENT_CACHE_SYNC
bool
#define ARCH_ZONE_DMA_BITS 24
#endif
-/*
- * For AMD SEV all DMA must be to unencrypted addresses.
- */
-static inline bool force_dma_unencrypted(void)
-{
- return sev_active();
-}
-
static void report_addr(struct device *dev, dma_addr_t dma_addr, size_t size)
{
if (!dev->dma_mask) {
static inline dma_addr_t phys_to_dma_direct(struct device *dev,
phys_addr_t phys)
{
- if (force_dma_unencrypted())
+ if (force_dma_unencrypted(dev))
return __phys_to_dma(dev, phys);
return phys_to_dma(dev, phys);
}
if (dev->bus_dma_mask && dev->bus_dma_mask < dma_mask)
dma_mask = dev->bus_dma_mask;
- if (force_dma_unencrypted())
+ if (force_dma_unencrypted(dev))
*phys_mask = __dma_to_phys(dev, dma_mask);
else
*phys_mask = dma_to_phys(dev, dma_mask);
}
ret = page_address(page);
- if (force_dma_unencrypted()) {
+ if (force_dma_unencrypted(dev)) {
set_memory_decrypted((unsigned long)ret, 1 << get_order(size));
*dma_handle = __phys_to_dma(dev, page_to_phys(page));
} else {
return;
}
- if (force_dma_unencrypted())
+ if (force_dma_unencrypted(dev))
set_memory_encrypted((unsigned long)cpu_addr, 1 << page_order);
if (IS_ENABLED(CONFIG_ARCH_HAS_UNCACHED_SEGMENT) &&