| Date | Wed, 16 Mar 2022 15:24:30 -0700 | From | Dave Hansen <> | Subject | Re: [PATCHv6 27/30] x86/kvm: Make SWIOTLB buffer shared for TD guest |
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On 3/15/22 19:08, Kirill A. Shutemov wrote: > 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. > > Make SWIOTLB buffer shared by generalizing mem_encrypt_init() to cover > TDX.
This could have saved me a trip to the console if it would have also said:
Stop selecting DYNAMIC_PHYSICAL_MASK directly. It will get set indirectly by selcting X86_MEM_ENCRYPT.
It's probably also worth noting:
mem_encrypt_init() is currently under an AMD-specific #ifdef. Move it to a more generic area of the header.
The other adorable thing about this patch:
> arch/x86/Kconfig | 2 +- > arch/x86/coco/core.c | 1 + > arch/x86/include/asm/mem_encrypt.h | 6 +++--- > arch/x86/mm/mem_encrypt.c | 9 ++++++++- > 4 files changed, 13 insertions(+), 5 deletions(-)
Is that it superficially has *zero* to do with SWIOTLB, also known as the declared Subject. It almost looks like this patch found a smaller and weaker patch, beat it up, and stole its Subject.
I'd be fine with an "x86/mm" tag on this too. I'm not sure what makes it truly KVM-specific.
Can you send a revision with something a bit more descriptive, please?
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