* Dan Williams <[email protected]> wrote:

> In preparation for using set_memory_uc() instead set_memory_np() for
> isolating poison from speculation, teach the memtype code to sanitize
> physical addresses vs __PHYSICAL_MASK.
> 
> The motivation for using set_memory_uc() for this case is to allow
> ongoing access to persistent memory pages via the pmem-driver +
> memcpy_mcsafe() until the poison is repaired.
> 
> Cc: Thomas Gleixner <[email protected]>
> Cc: Ingo Molnar <[email protected]>
> Cc: "H. Peter Anvin" <[email protected]>
> Cc: Tony Luck <[email protected]>
> Cc: Borislav Petkov <[email protected]>
> Cc: <[email protected]>
> Cc: <[email protected]>
> Signed-off-by: Dan Williams <[email protected]>
> ---
>  arch/x86/mm/pat.c |   16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
> 
> diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c
> index 1555bd7d3449..6788ffa990f8 100644
> --- a/arch/x86/mm/pat.c
> +++ b/arch/x86/mm/pat.c
> @@ -512,6 +512,17 @@ static int free_ram_pages_type(u64 start, u64 end)
>       return 0;
>  }
>  
> +static u64 sanitize_phys(u64 address)
> +{
> +     /*
> +      * When changing the memtype for pages containing poison allow
> +      * for a "decoy" virtual address (bit 63 clear) passed to
> +      * set_memory_X(). __pa() on a "decoy" address results in a
> +      * physical address with it 63 set.
> +      */
> +     return address & __PHYSICAL_MASK;

s/it/bit

Thanks,

        Ingo
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