Messages in this thread | | | Date | Thu, 26 May 2022 13:39:37 -0700 | Subject | Re: [PATCHv3 3/3] x86/tdx: Handle load_unaligned_zeropad() page-cross to a shared page | From | Dave Hansen <> |
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On 5/26/22 13:36, Kirill A. Shutemov wrote: > On Thu, May 26, 2022 at 09:20:56AM -0700, Dave Hansen wrote: >> On 5/24/22 15:10, Kirill A. Shutemov wrote: >>> + /* >>> + * MMIO accesses suppose to be naturally aligned and therefore never >>> + * cross a page boundary. Seeing unaligned accesses indicates a bug or >>> + * load_unaligned_zeropad() that steps into unmapped shared page. >> Wait a sec though... >> >> We've been talking all along about how MMIO accesses are in some cases >> just plain old compiler-generated memory accesses. It's *probably* bad >> code that does this, but it's not necessarily a bug. > Compiler-generated memory accesses tend to be aligned too. You need to do > something make them unalinged, like __packed or pointer trickery.
I totally agree. But, the point is that __packed or pointer trickery is goofy, but it's not necessarily a bug. This might crash the kernel on goofy stuff, not bugs.
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