linux-kernel - Re: [PATCH, RFC 19/62] x86/mm: Handle encrypted memory in page_to_virt() and _

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Date:   Fri, 14 Jun 2019 13:10:12 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>, x86@...nel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, Borislav Petkov <bp@...en8.de>,
        Andy Lutomirski <luto@...capital.net>,
        David Howells <dhowells@...hat.com>,
        Kees Cook <keescook@...omium.org>,
        Dave Hansen <dave.hansen@...el.com>,
        Kai Huang <kai.huang@...ux.intel.com>,
        Jacob Pan <jacob.jun.pan@...ux.intel.com>,
        Alison Schofield <alison.schofield@...el.com>,
        linux-mm@...ck.org, kvm@...r.kernel.org, keyrings@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH, RFC 19/62] x86/mm: Handle encrypted memory in
 page_to_virt() and __pa()

On Wed, May 08, 2019 at 05:43:39PM +0300, Kirill A. Shutemov wrote:
> Per-KeyID direct mappings require changes into how we find the right
> virtual address for a page and virt-to-phys address translations.
> 
> page_to_virt() definition overwrites default macros provided by
> <linux/mm.h>.
> 
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
> ---
>  arch/x86/include/asm/page.h    | 3 +++
>  arch/x86/include/asm/page_64.h | 2 +-
>  2 files changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/include/asm/page.h b/arch/x86/include/asm/page.h
> index 39af59487d5f..aff30554f38e 100644
> --- a/arch/x86/include/asm/page.h
> +++ b/arch/x86/include/asm/page.h
> @@ -72,6 +72,9 @@ static inline void copy_user_page(void *to, void *from, unsigned long vaddr,
>  extern bool __virt_addr_valid(unsigned long kaddr);
>  #define virt_addr_valid(kaddr)	__virt_addr_valid((unsigned long) (kaddr))
>  
> +#define page_to_virt(x) \
> +	(__va(PFN_PHYS(page_to_pfn(x))) + page_keyid(x) * direct_mapping_size)
> +
>  #endif	/* __ASSEMBLY__ */

So this is the bit that makes patch 13 make sense. It would've been nice
to have that called out in the Changelog or something.