From 968b493173ac5205fe75f6330ee767f96bf88e57 Mon Sep 17 00:00:00 2001 From: "Kirill A. Shutemov" Date: Wed, 6 Apr 2022 02:29:36 +0300 Subject: 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 Signed-off-by: Kuppuswamy Sathyanarayanan Signed-off-by: Kirill A. Shutemov Signed-off-by: Dave Hansen Reviewed-by: Andi Kleen Reviewed-by: Tony Luck Reviewed-by: Dave Hansen Link: https://lkml.kernel.org/r/20220405232939.73860-28-kirill.shutemov@linux.intel.com --- arch/x86/coco/core.c | 1 + 1 file changed, 1 insertion(+) (limited to 'arch/x86/coco') diff --git a/arch/x86/coco/core.c b/arch/x86/coco/core.c index 9f74125c582d..4320fadae716 100644 --- a/arch/x86/coco/core.c +++ b/arch/x86/coco/core.c @@ -22,6 +22,7 @@ static bool intel_cc_platform_has(enum cc_attr attr) case CC_ATTR_GUEST_UNROLL_STRING_IO: case CC_ATTR_HOTPLUG_DISABLED: case CC_ATTR_GUEST_MEM_ENCRYPT: + case CC_ATTR_MEM_ENCRYPT: return true; default: return false; -- cgit v1.2.3