[PATCH] x86/mm: fix dump_pagetables with Xen PV

[PATCH] x86/mm: fix dump_pagetables with Xen PV

[Juergen Gross]

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@xen.org>
Signed-off-by: Juergen Gross <jgross@suse.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
-- 
2.16.4

Re: [Xen-devel] [PATCH] x86/mm: fix dump_pagetables with Xen PV

[Julien Grall]

Hi Juergen,

On 21/02/2020 10:38, 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@xen.org>
> Signed-off-by: Juergen Gross <jgross@suse.com>

I can confirm the crash has now disappeared:

Tested-by: Julien Grall <julien@xen.org>

Cheers,

-- 
Julien Grall

Re: [PATCH] x86/mm: fix dump_pagetables with Xen PV

[Jürgen Groß]

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@xen.org>
> Signed-off-by: Juergen Gross <jgross@suse.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
> 

[tip: x86/urgent] x86/mm: Fix dump_pagetables with Xen PV

[tip-bot2 for Juergen Gross]

The following commit has been merged into the x86/urgent branch of tip:

Commit-ID:     bba42affa732d6fd5bd5c9678e6deacde2de1547
Gitweb:        https://git.kernel.org/tip/bba42affa732d6fd5bd5c9678e6deacde2de1547
Author:        Juergen Gross <jgross@suse.com>
AuthorDate:    Fri, 21 Feb 2020 11:38:51 +01:00
Committer:     Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Sat, 29 Feb 2020 12:43:10 +01:00

x86/mm: Fix dump_pagetables with Xen PV

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@xen.org>
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Julien Grall <julien@xen.org>
Link: https://lkml.kernel.org/r/20200221103851.7855-1-jgross@suse.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 64229da..69309cd 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