Messages in this thread | | | Date | Mon, 21 Feb 2022 12:31:40 -0600 | Subject | Re: [PATCHv3.1 2.1/2] x86/coco: Add API to handle encryption mask | From | Tom Lendacky <> |
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On 2/18/22 18:13, Kirill A. Shutemov wrote: > AMD SME/SEV uses a bit in the page table entries to indicate that the > page is encrypted and not accessible to the VMM. > > TDX uses a similar approach, but the polarity of the mask is opposite to > AMD: if the bit is set the page is accessible to VMM. > > Provide vendor-neutral API to deal with the mask: > > - cc_mkenc() and cc_mkdec() modify given address to make it > encrypted/decrypted. It can be applied to phys_addr_t, pgprotval_t > or page table entry value. > > - cc_get_mask() returns encryption or decrypthion mask. It is useful > for set_memory_encrypted() and set_memory_decrypted() > implementation. > > The implementation will be extended to cover TDX. > > pgprot_decrypted() is used by drivers (i915, virtio_gpu, vfio). > cc_mkdec() called by pgprot_decrypted(). Export cc_mkdec(). > > HyperV doesn't use bits in page table entries, so the mask is 0 for both > encrypthion and decrypthion. > > Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> @@ -84,7 +85,39 @@ bool cc_platform_has(enum cc_attr attr) > } > EXPORT_SYMBOL_GPL(cc_platform_has); > > -__init void cc_init(enum cc_vendor vendor) > +u64 cc_get_mask(bool enc)
I was a bit confused by this name, expecting to always get the mask, but it is dependent on the input parameter. How about cc_get_operation_mask() or ... ? I'm struggling to come up with a good name, but plain cc_get_mask() is very confusing.
> +{ > + switch (cc_vendor) { > + case CC_VENDOR_AMD: > + return enc ? cc_mask : 0; > + default: > + return 0; > + } > +} > +
> diff --git a/arch/x86/mm/mem_encrypt_identity.c b/arch/x86/mm/mem_encrypt_identity.c > index eb7fbd85b77e..fa758247ab57 100644 > --- a/arch/x86/mm/mem_encrypt_identity.c > +++ b/arch/x86/mm/mem_encrypt_identity.c > @@ -603,5 +603,5 @@ void __init sme_enable(struct boot_params *bp) > out: > physical_mask &= ~sme_me_mask; > if (sme_me_mask) > - cc_init(CC_VENDOR_AMD); > + cc_init(CC_VENDOR_AMD, sme_me_mask);
Since you're adding the if statement, you can probably wrap the adjustment to physical_mask within the if, also (I guess in the previous patch). Not required, though.
Thanks, Tom
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