Messages in this thread | | | Date | Tue, 22 Feb 2022 01:14:24 +0300 | From | "Kirill A. Shutemov" <> | Subject | Re: [PATCHv3.1 2.1/2] x86/coco: Add API to handle encryption mask |
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On Mon, Feb 21, 2022 at 12:31:40PM -0600, Tom Lendacky wrote: > 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.
Well, it always get you a mask. But it can be empty :P
> 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.
Yeah. Naming is hard. cc_get_operation_mask() doesn't clarify anything comparing to cc_get_mask(). To me it is as 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.
Can do.
-- Kirill A. Shutemov
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