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| author | Kirill A. Shutemov <kirill.shutemov@linux.intel.com> | 2022-04-06 02:29:36 +0300 |
|---|---|---|
| committer | Dave Hansen <dave.hansen@linux.intel.com> | 2022-04-07 08:27:53 -0700 |
| commit | 968b493173ac5205fe75f6330ee767f96bf88e57 (patch) | |
| tree | c564f9238c479c9edf4e51340b42d20720e19215 /arch/x86/Kconfig | |
| parent | 7dbde7631629896b478bc5b1f4c3e52e6d518d12 (diff) | |
| download | lwn-968b493173ac5205fe75f6330ee767f96bf88e57.tar.gz lwn-968b493173ac5205fe75f6330ee767f96bf88e57.zip | |
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/Kconfig')
| -rw-r--r-- | arch/x86/Kconfig | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index a18185525708..7021ec725dd3 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -883,7 +883,7 @@ config INTEL_TDX_GUEST depends on X86_64 && CPU_SUP_INTEL depends on X86_X2APIC select ARCH_HAS_CC_PLATFORM - select DYNAMIC_PHYSICAL_MASK + select X86_MEM_ENCRYPT select X86_MCE help Support running as a guest under Intel TDX. Without this support, |