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authorKirill A. Shutemov <kirill.shutemov@linux.intel.com>2022-04-06 02:29:36 +0300
committerDave Hansen <dave.hansen@linux.intel.com>2022-04-07 08:27:53 -0700
commit968b493173ac5205fe75f6330ee767f96bf88e57 (patch)
treec564f9238c479c9edf4e51340b42d20720e19215 /arch/x86/mm
parent7dbde7631629896b478bc5b1f4c3e52e6d518d12 (diff)
downloadlinux-next-968b493173ac5205fe75f6330ee767f96bf88e57.tar.gz
x86/mm: Make DMA memory shared for TD guest
Intel TDX doesn't allow VMM to directly access guest private memory. Any memory that is required for communication with the VMM must be shared explicitly. The same rule applies for any DMA to and from the TDX guest. All DMA pages have to be marked as shared pages. A generic way to achieve this without any changes to device drivers is to use the SWIOTLB framework. The previous patch ("Add support for TDX shared memory") gave TDX guests the _ability_ to make some pages shared, but did not make any pages shared. This actually marks SWIOTLB buffers *as* shared. Start returning true for cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT) in TDX guests. This has several implications: - Allows the existing mem_encrypt_init() to be used for TDX which sets SWIOTLB buffers shared (aka. "decrypted"). - Ensures that all DMA is routed via the SWIOTLB mechanism (see pci_swiotlb_detect()) Stop selecting DYNAMIC_PHYSICAL_MASK directly. It will get set indirectly by selecting X86_MEM_ENCRYPT. mem_encrypt_init() is currently under an AMD-specific #ifdef. Move it to a generic area of the header. Co-developed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com> Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Andi Kleen <ak@linux.intel.com> Reviewed-by: Tony Luck <tony.luck@intel.com> Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com> Link: https://lkml.kernel.org/r/20220405232939.73860-28-kirill.shutemov@linux.intel.com
Diffstat (limited to 'arch/x86/mm')
-rw-r--r--arch/x86/mm/mem_encrypt.c9
1 files changed, 8 insertions, 1 deletions
diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c
index 50d209939c66..10ee40b5204b 100644
--- a/arch/x86/mm/mem_encrypt.c
+++ b/arch/x86/mm/mem_encrypt.c
@@ -42,7 +42,14 @@ bool force_dma_unencrypted(struct device *dev)
static void print_mem_encrypt_feature_info(void)
{
- pr_info("AMD Memory Encryption Features active:");
+ pr_info("Memory Encryption Features active:");
+
+ if (cpu_feature_enabled(X86_FEATURE_TDX_GUEST)) {
+ pr_cont(" Intel TDX\n");
+ return;
+ }
+
+ pr_cont("AMD ");
/* Secure Memory Encryption */
if (cc_platform_has(CC_ATTR_HOST_MEM_ENCRYPT)) {