Re: [PATCH 1/2] x86/mce: Fix missing address mask in recovery for errors in TDX/SEAM non-root mode

[Xiaoyao Li]

On 6/18/2025 8:08 PM, Adrian Hunter wrote:
> Commit 8a01ec97dc066 ("x86/mce: Mask out non-address bits from machine
> check bank") introduced a new #define MCI_ADDR_PHYSADDR for the mask of
> valid physical address bits within the machine check bank address register.
>
> This is particularly needed in the case of errors in TDX/SEAM non-root mode
> because the reported address contains the TDX KeyID.  Refer to TDX and
> TME-MK documentation for more information about KeyIDs.
>
> Commit 7911f145de5fe ("x86/mce: Implement recovery for errors in TDX/SEAM
> non-root mode") uses the address to mark the affected page as poisoned, but
> omits to use the aforementioned mask.
>
> Mask the address with MCI_ADDR_PHYSADDR so that the page can be found.
>
> Fixes: 7911f145de5fe ("x86/mce: Implement recovery for errors in TDX/SEAM non-root mode")
> Cc: stable@xxxxxxxxxxxxxxx

Reviewed-by: Xiaoyao Li <xiaoyao.li@xxxxxxxxx>

> Signed-off-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
> ---
>   arch/x86/kernel/cpu/mce/core.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
> index e9b3c5d4a52e..76c4634c6a5f 100644
> --- a/arch/x86/kernel/cpu/mce/core.c
> +++ b/arch/x86/kernel/cpu/mce/core.c
> @@ -1665,7 +1665,8 @@ noinstr void do_machine_check(struct pt_regs *regs)
>   		 * be added to free list when the guest is terminated.
>   		 */
>   		if (mce_usable_address(m)) {
> -			struct page *p = pfn_to_online_page(m->addr >> PAGE_SHIFT);
> +			unsigned long pfn = (m->addr & MCI_ADDR_PHYSADDR) >> PAGE_SHIFT;
> +			struct page *p = pfn_to_online_page(pfn);
>   
>   			if (p)
>   				SetPageHWPoison(p);