Re: [PATCH] x86/mm/cpa: set PAGE_KERNEL in __set_pages_p()

[Tom Lendacky <thomas.lendacky@amd.com>]

On 5/6/22 00:19, Hyeonggon Yoo wrote:
> __set_pages_np() not only clears _PAGE_PRESENT and _PAGE_RW, but also
> clears _PAGE_GLOBAL to avoid confusing _PAGE_GLOBAL as _PAGE_PROTNONE
> when the PTE is not present.
> 
> Common usage for __set_pages_p() is to call it after __set_pages_np().
> Therefore calling __set_pages_p() after __set_pages_np() clears
> _PAGE_GLOBAL, making it unable to globally shared in TLB.
> 
> As they are called by set_direct_map_{invalid,default}_noflush(),
> pages in direct map cannot be globally shared in TLB after being used by
> vmalloc, secretmem, and hibernation.
> 
> So set PAGE_KERNEL isntead of __pgprot(_PAGE_PRESENT | _PAGE_RW) in
> __set_pages_p().
> 
> Signed-off-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
> ---
>   arch/x86/mm/pat/set_memory.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c
> index abf5ed76e4b7..fcb6147c4cd4 100644
> --- a/arch/x86/mm/pat/set_memory.c
> +++ b/arch/x86/mm/pat/set_memory.c
> @@ -2177,7 +2177,7 @@ static int __set_pages_p(struct page *page, int numpages)
>   	struct cpa_data cpa = { .vaddr = &tempaddr,
>   				.pgd = NULL,
>   				.numpages = numpages,
> -				.mask_set = __pgprot(_PAGE_PRESENT | _PAGE_RW),
> +				.mask_set = PAGE_KERNEL,

With SME/SEV, this will also (unintentionally) set the encryption bit, so 
I don't think this is correct.

Thanks,
Tom

>   				.mask_clr = __pgprot(0),
>   				.flags = 0};
>