linux-kernel - Re: [PATCH] x86/mm: fix dump

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Date:   Fri, 28 Feb 2020 16:30:51 +0100
From:   Jürgen Groß <jgross@...e.com>
To:     xen-devel@...ts.xenproject.org, x86@...nel.org,
        linux-kernel@...r.kernel.org
Cc:     Dave Hansen <dave.hansen@...ux.intel.com>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH] x86/mm: fix dump_pagetables with Xen PV

Friendly ping...

On 21.02.20 11:38, Juergen Gross wrote:
> Commit 2ae27137b2db89 ("x86: mm: convert dump_pagetables to use
> walk_page_range") broke Xen PV guests as the hypervisor reserved hole
> in the memory map was not taken into account.
> 
> Fix that by starting the kernel range only at GUARD_HOLE_END_ADDR.
> 
> Fixes: 2ae27137b2db89 ("x86: mm: convert dump_pagetables to use walk_page_range")
> Reported-by: Julien Grall <julien@....org>
> Signed-off-by: Juergen Gross <jgross@...e.com>
> ---
>   arch/x86/mm/dump_pagetables.c | 7 +------
>   1 file changed, 1 insertion(+), 6 deletions(-)
> 
> diff --git a/arch/x86/mm/dump_pagetables.c b/arch/x86/mm/dump_pagetables.c
> index 64229dad7eab..69309cd56fdf 100644
> --- a/arch/x86/mm/dump_pagetables.c
> +++ b/arch/x86/mm/dump_pagetables.c
> @@ -363,13 +363,8 @@ static void ptdump_walk_pgd_level_core(struct seq_file *m,
>   {
>   	const struct ptdump_range ptdump_ranges[] = {
>   #ifdef CONFIG_X86_64
> -
> -#define normalize_addr_shift (64 - (__VIRTUAL_MASK_SHIFT + 1))
> -#define normalize_addr(u) ((signed long)((u) << normalize_addr_shift) >> \
> -			   normalize_addr_shift)
> -
>   	{0, PTRS_PER_PGD * PGD_LEVEL_MULT / 2},
> -	{normalize_addr(PTRS_PER_PGD * PGD_LEVEL_MULT / 2), ~0UL},
> +	{GUARD_HOLE_END_ADDR, ~0UL},
>   #else
>   	{0, ~0UL},
>   #endif
>