Messages in this thread | | | From | "Edgecombe, Rick P" <> | Subject | Re: [PATCH] x86/tdx: Preserve shared bit on mprotect() | Date | Fri, 12 Apr 2024 20:48:56 +0000 |
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On Fri, 2024-04-12 at 22:12 +0300, Kirill A. Shutemov wrote: > The TDX guest platform takes one bit from the physical address to > indicate if the page is shared (accessible by VMM). This bit is not part > of the physical_mask and is not preserved during mprotect(). As a > result, the 'shared' bit is lost during mprotect() on shared mappings. > > _COMMON_PAGE_CHG_MASK specifies which PTE bits need to be preserved > during modification. AMD includes 'sme_me_mask' in the define to > preserve the 'encrypt' bit. > > To cover both Intel and AMD cases, include 'cc_mask' in > _COMMON_PAGE_CHG_MASK instead of 'sme_me_mask'. > > Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> > Fixes: 41394e33f3a0 ("x86/tdx: Extend the confidential computing API to > support TDX guests") > Cc: Tom Lendacky <thomas.lendacky@amd.com> > Cc: Chris Oo <cho@microsoft.com> > Cc: Dexuan Cui <decui@microsoft.com>
Reviewed-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
So does this mean there is shared memory mapped to userspace? Or is this a theoretical correctness thing?
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