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[PATCH v2] x86/efi: Disable runtime services on kexec kernel if booted with efi=old_map

Started bySai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
First post2017-05-17 03:20 +0200
Last post2017-05-25 14:00 +0200
Articles 5 — 4 participants

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  [PATCH v2] x86/efi: Disable runtime services on kexec kernel if booted with efi=old_map Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com> - 2017-05-17 03:20 +0200
    Re: [PATCH v2] x86/efi: Disable runtime services on kexec kernel if  booted with efi=old_map Dave Young <dyoung@redhat.com> - 2017-05-17 04:00 +0200
      Re: [PATCH v2] x86/efi: Disable runtime services on kexec kernel if  booted with efi=old_map Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com> - 2017-05-17 04:10 +0200
    Re: [PATCH v2] x86/efi: Disable runtime services on kexec kernel if  booted with efi=old_map joeyli <jlee@suse.com> - 2017-05-17 09:30 +0200
    Re: [PATCH v2] x86/efi: Disable runtime services on kexec kernel if  booted with efi=old_map Matt Fleming <matt@codeblueprint.co.uk> - 2017-05-25 14:00 +0200

#1642911 — [PATCH v2] x86/efi: Disable runtime services on kexec kernel if booted with efi=old_map

FromSai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
Date2017-05-17 03:20 +0200
Subject[PATCH v2] x86/efi: Disable runtime services on kexec kernel if booted with efi=old_map
Message-ID<tHVN7-4OT-11@gated-at.bofh.it>
From: Sai Praneeth <sai.praneeth.prakhya@intel.com>

Booting kexec kernel with "efi=old_map" in kernel command line hits
kernel panic as shown below.

[0.001000] BUG: unable to handle kernel paging request at ffff88007fe78070
[0.001000] IP: virt_efi_set_variable.part.7+0x63/0x1b0
[0.001000] PGD 7ea28067
[0.001000] PUD 7ea2b067
[0.001000] PMD 7ea2d067
[0.001000] PTE 0
[0.001000]
[0.001000] Oops: 0000 [#1] SMP
[0.001000] Modules linked in:
[0.001000] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.11.0-rc2-yocto-standard+ #229
[0.001000] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 0.0.0 02/06/2015
[0.001000] task: ffffffff82022500 task.stack: ffffffff82000000
[0.001000] RIP: 0010:virt_efi_set_variable.part.7+0x63/0x1b0
[0.001000] RSP: 0000:ffffffff82003dc0 EFLAGS: 00010246
[0.001000] RAX: ffff88007fe78018 RBX: ffffffff82050300 RCX: 0000000000000007
[0.001000] RDX: ffffffff82003e50 RSI: ffffffff82050300 RDI: ffffffff82050300
[0.001000] RBP: ffffffff82003e08 R08: 0000000000000000 R09: 0000000000000000
[0.001000] R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff82003e50
[0.001000] R13: 0000000000000007 R14: 0000000000000246 R15: 0000000000000000
[0.001000] FS:  0000000000000000(0000) GS:ffff88007fa00000(0000) knlGS:0000000000000000
[0.001000] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[0.001000] CR2: ffff88007fe78070 CR3: 000000007da1d000 CR4: 00000000000006b0
[0.001000] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[0.001000] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[0.001000] Call Trace:
[0.001000]  virt_efi_set_variable+0x5d/0x70
[0.001000]  efi_delete_dummy_variable+0x7a/0x80
[0.001000]  efi_enter_virtual_mode+0x3f6/0x4a7
[0.001000]  start_kernel+0x375/0x400
[0.001000]  x86_64_start_reservations+0x2a/0x2c
[0.001000]  x86_64_start_kernel+0x168/0x176
[0.001000]  start_cpu+0x14/0x14
[0.001000] Code: 04 b0 84 ff 80 3d c5 56 b3 00 00 4c 8b 44 24 08 75
6b 9c 41 5e 48 8b 05 9c 78 99 00 4d 89 c1 48 89 de 4d 89 f8 44 89 e9 4c
89 e2 <48> 8b 40 58 48 8b 78 58 e8 b0 2d 88 ff 48 c7 c6 b6 1d f4 81 4c
[0.001000] RIP: virt_efi_set_variable.part.7+0x63/0x1b0 RSP: ffffffff82003dc0
[0.001000] CR2: ffff88007fe78070
[0.001000] ---[ end trace 0000000000000000 ]---
[0.001000] Kernel panic - not syncing: Attempted to kill the idle task!
[0.001000] ---[ end Kernel panic - not syncing: Attempted to kill the idle task!

[efi=old_map was never intended to work with kexec. The problem with
using efi=old_map is that the virtual addresses are assigned from the
memory region used by other kernel mappings; vmalloc() space.
Potentially there could be collisions when booting kexec if something
else is mapped at the virtual address we allocated for runtime service
regions in the initial boot] - Matt Fleming

Since kexec was never intended to work with efi=old_map, disable
runtime services in kexec if booted with efi=old_map, so that we don't
panic.

Signed-off-by: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Ricardo Neri <ricardo.neri@intel.com>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Ravi Shankar <ravi.v.shankar@intel.com>
Cc: Lee Chun-Yi <jlee@suse.com>
Cc: Dave Young <dyoung@redhat.com>

Changes since v1:
Don't fix the panic, because this was never intended to work.
---
 arch/x86/platform/efi/efi.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
index 87835c97611f..627b7b86f369 100644
--- a/arch/x86/platform/efi/efi.c
+++ b/arch/x86/platform/efi/efi.c
@@ -827,9 +827,11 @@ static void __init kexec_enter_virtual_mode(void)
 
 	/*
 	 * We don't do virtual mode, since we don't do runtime services, on
-	 * non-native EFI
+	 * non-native EFI. With efi=old_map, we don't do runtime services in
+	 * kexec kernel because in the initial boot something else might
+	 * have been mapped at these virtual addresses.
 	 */
-	if (!efi_is_native()) {
+	if (!efi_is_native() || efi_enabled(EFI_OLD_MEMMAP)) {
 		efi_memmap_unmap();
 		clear_bit(EFI_RUNTIME_SERVICES, &efi.flags);
 		return;
-- 
2.1.4

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#1642916 — Re: [PATCH v2] x86/efi: Disable runtime services on kexec kernel if booted with efi=old_map

FromDave Young <dyoung@redhat.com>
Date2017-05-17 04:00 +0200
SubjectRe: [PATCH v2] x86/efi: Disable runtime services on kexec kernel if booted with efi=old_map
Message-ID<tHWpP-55l-1@gated-at.bofh.it>
In reply to#1642911
Hi Sai,
On 05/16/17 at 06:14pm, Sai Praneeth Prakhya wrote:
> From: Sai Praneeth <sai.praneeth.prakhya@intel.com>
> 
> Booting kexec kernel with "efi=old_map" in kernel command line hits
> kernel panic as shown below.
> 
> [0.001000] BUG: unable to handle kernel paging request at ffff88007fe78070
> [0.001000] IP: virt_efi_set_variable.part.7+0x63/0x1b0
> [0.001000] PGD 7ea28067
> [0.001000] PUD 7ea2b067
> [0.001000] PMD 7ea2d067
> [0.001000] PTE 0
> [0.001000]
> [0.001000] Oops: 0000 [#1] SMP
> [0.001000] Modules linked in:
> [0.001000] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.11.0-rc2-yocto-standard+ #229
> [0.001000] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 0.0.0 02/06/2015
> [0.001000] task: ffffffff82022500 task.stack: ffffffff82000000
> [0.001000] RIP: 0010:virt_efi_set_variable.part.7+0x63/0x1b0
> [0.001000] RSP: 0000:ffffffff82003dc0 EFLAGS: 00010246
> [0.001000] RAX: ffff88007fe78018 RBX: ffffffff82050300 RCX: 0000000000000007
> [0.001000] RDX: ffffffff82003e50 RSI: ffffffff82050300 RDI: ffffffff82050300
> [0.001000] RBP: ffffffff82003e08 R08: 0000000000000000 R09: 0000000000000000
> [0.001000] R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff82003e50
> [0.001000] R13: 0000000000000007 R14: 0000000000000246 R15: 0000000000000000
> [0.001000] FS:  0000000000000000(0000) GS:ffff88007fa00000(0000) knlGS:0000000000000000
> [0.001000] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [0.001000] CR2: ffff88007fe78070 CR3: 000000007da1d000 CR4: 00000000000006b0
> [0.001000] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> [0.001000] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> [0.001000] Call Trace:
> [0.001000]  virt_efi_set_variable+0x5d/0x70
> [0.001000]  efi_delete_dummy_variable+0x7a/0x80
> [0.001000]  efi_enter_virtual_mode+0x3f6/0x4a7
> [0.001000]  start_kernel+0x375/0x400
> [0.001000]  x86_64_start_reservations+0x2a/0x2c
> [0.001000]  x86_64_start_kernel+0x168/0x176
> [0.001000]  start_cpu+0x14/0x14
> [0.001000] Code: 04 b0 84 ff 80 3d c5 56 b3 00 00 4c 8b 44 24 08 75
> 6b 9c 41 5e 48 8b 05 9c 78 99 00 4d 89 c1 48 89 de 4d 89 f8 44 89 e9 4c
> 89 e2 <48> 8b 40 58 48 8b 78 58 e8 b0 2d 88 ff 48 c7 c6 b6 1d f4 81 4c
> [0.001000] RIP: virt_efi_set_variable.part.7+0x63/0x1b0 RSP: ffffffff82003dc0
> [0.001000] CR2: ffff88007fe78070
> [0.001000] ---[ end trace 0000000000000000 ]---
> [0.001000] Kernel panic - not syncing: Attempted to kill the idle task!
> [0.001000] ---[ end Kernel panic - not syncing: Attempted to kill the idle task!
> 
> [efi=old_map was never intended to work with kexec. The problem with
> using efi=old_map is that the virtual addresses are assigned from the
> memory region used by other kernel mappings; vmalloc() space.
> Potentially there could be collisions when booting kexec if something
> else is mapped at the virtual address we allocated for runtime service
> regions in the initial boot] - Matt Fleming
> 
> Since kexec was never intended to work with efi=old_map, disable
> runtime services in kexec if booted with efi=old_map, so that we don't
> panic.
> 
> Signed-off-by: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
> Cc: Borislav Petkov <bp@alien8.de>
> Cc: Ricardo Neri <ricardo.neri@intel.com>
> Cc: Matt Fleming <matt@codeblueprint.co.uk>
> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> Cc: Ravi Shankar <ravi.v.shankar@intel.com>
> Cc: Lee Chun-Yi <jlee@suse.com>
> Cc: Dave Young <dyoung@redhat.com>
> 
> Changes since v1:
> Don't fix the panic, because this was never intended to work.
> ---
>  arch/x86/platform/efi/efi.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
> index 87835c97611f..627b7b86f369 100644
> --- a/arch/x86/platform/efi/efi.c
> +++ b/arch/x86/platform/efi/efi.c
> @@ -827,9 +827,11 @@ static void __init kexec_enter_virtual_mode(void)
>  
>  	/*
>  	 * We don't do virtual mode, since we don't do runtime services, on
> -	 * non-native EFI
> +	 * non-native EFI. With efi=old_map, we don't do runtime services in
> +	 * kexec kernel because in the initial boot something else might
> +	 * have been mapped at these virtual addresses.
>  	 */
> -	if (!efi_is_native()) {
> +	if (!efi_is_native() || efi_enabled(EFI_OLD_MEMMAP)) {
>  		efi_memmap_unmap();
>  		clear_bit(EFI_RUNTIME_SERVICES, &efi.flags);
>  		return;
> -- 
> 2.1.4
> 

Suppose it has passed the test on your hardware:
Acked-by: Dave Young <dyoung@redhat.com>

Thanks
Dave

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#1642917 — Re: [PATCH v2] x86/efi: Disable runtime services on kexec kernel if booted with efi=old_map

FromSai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
Date2017-05-17 04:10 +0200
SubjectRe: [PATCH v2] x86/efi: Disable runtime services on kexec kernel if booted with efi=old_map
Message-ID<tHWzv-5oI-1@gated-at.bofh.it>
In reply to#1642916
On Wed, 2017-05-17 at 09:57 +0800, Dave Young wrote:
> Hi Sai,
> On 05/16/17 at 06:14pm, Sai Praneeth Prakhya wrote:
> > From: Sai Praneeth <sai.praneeth.prakhya@intel.com>
> > 
> > Booting kexec kernel with "efi=old_map" in kernel command line hits
> > kernel panic as shown below.
> > 
> > [0.001000] BUG: unable to handle kernel paging request at ffff88007fe78070
> > [0.001000] IP: virt_efi_set_variable.part.7+0x63/0x1b0
> > [0.001000] PGD 7ea28067
> > [0.001000] PUD 7ea2b067
> > [0.001000] PMD 7ea2d067
> > [0.001000] PTE 0
> > [0.001000]
> > [0.001000] Oops: 0000 [#1] SMP
> > [0.001000] Modules linked in:
> > [0.001000] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.11.0-rc2-yocto-standard+ #229
> > [0.001000] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 0.0.0 02/06/2015
> > [0.001000] task: ffffffff82022500 task.stack: ffffffff82000000
> > [0.001000] RIP: 0010:virt_efi_set_variable.part.7+0x63/0x1b0
> > [0.001000] RSP: 0000:ffffffff82003dc0 EFLAGS: 00010246
> > [0.001000] RAX: ffff88007fe78018 RBX: ffffffff82050300 RCX: 0000000000000007
> > [0.001000] RDX: ffffffff82003e50 RSI: ffffffff82050300 RDI: ffffffff82050300
> > [0.001000] RBP: ffffffff82003e08 R08: 0000000000000000 R09: 0000000000000000
> > [0.001000] R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff82003e50
> > [0.001000] R13: 0000000000000007 R14: 0000000000000246 R15: 0000000000000000
> > [0.001000] FS:  0000000000000000(0000) GS:ffff88007fa00000(0000) knlGS:0000000000000000
> > [0.001000] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > [0.001000] CR2: ffff88007fe78070 CR3: 000000007da1d000 CR4: 00000000000006b0
> > [0.001000] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> > [0.001000] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> > [0.001000] Call Trace:
> > [0.001000]  virt_efi_set_variable+0x5d/0x70
> > [0.001000]  efi_delete_dummy_variable+0x7a/0x80
> > [0.001000]  efi_enter_virtual_mode+0x3f6/0x4a7
> > [0.001000]  start_kernel+0x375/0x400
> > [0.001000]  x86_64_start_reservations+0x2a/0x2c
> > [0.001000]  x86_64_start_kernel+0x168/0x176
> > [0.001000]  start_cpu+0x14/0x14
> > [0.001000] Code: 04 b0 84 ff 80 3d c5 56 b3 00 00 4c 8b 44 24 08 75
> > 6b 9c 41 5e 48 8b 05 9c 78 99 00 4d 89 c1 48 89 de 4d 89 f8 44 89 e9 4c
> > 89 e2 <48> 8b 40 58 48 8b 78 58 e8 b0 2d 88 ff 48 c7 c6 b6 1d f4 81 4c
> > [0.001000] RIP: virt_efi_set_variable.part.7+0x63/0x1b0 RSP: ffffffff82003dc0
> > [0.001000] CR2: ffff88007fe78070
> > [0.001000] ---[ end trace 0000000000000000 ]---
> > [0.001000] Kernel panic - not syncing: Attempted to kill the idle task!
> > [0.001000] ---[ end Kernel panic - not syncing: Attempted to kill the idle task!
> > 
> > [efi=old_map was never intended to work with kexec. The problem with
> > using efi=old_map is that the virtual addresses are assigned from the
> > memory region used by other kernel mappings; vmalloc() space.
> > Potentially there could be collisions when booting kexec if something
> > else is mapped at the virtual address we allocated for runtime service
> > regions in the initial boot] - Matt Fleming
> > 
> > Since kexec was never intended to work with efi=old_map, disable
> > runtime services in kexec if booted with efi=old_map, so that we don't
> > panic.
> > 
> > Signed-off-by: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
> > Cc: Borislav Petkov <bp@alien8.de>
> > Cc: Ricardo Neri <ricardo.neri@intel.com>
> > Cc: Matt Fleming <matt@codeblueprint.co.uk>
> > Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> > Cc: Ravi Shankar <ravi.v.shankar@intel.com>
> > Cc: Lee Chun-Yi <jlee@suse.com>
> > Cc: Dave Young <dyoung@redhat.com>
> > 
> > Changes since v1:
> > Don't fix the panic, because this was never intended to work.
> > ---
> >  arch/x86/platform/efi/efi.c | 6 ++++--
> >  1 file changed, 4 insertions(+), 2 deletions(-)
> > 
> > diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
> > index 87835c97611f..627b7b86f369 100644
> > --- a/arch/x86/platform/efi/efi.c
> > +++ b/arch/x86/platform/efi/efi.c
> > @@ -827,9 +827,11 @@ static void __init kexec_enter_virtual_mode(void)
> >  
> >  	/*
> >  	 * We don't do virtual mode, since we don't do runtime services, on
> > -	 * non-native EFI
> > +	 * non-native EFI. With efi=old_map, we don't do runtime services in
> > +	 * kexec kernel because in the initial boot something else might
> > +	 * have been mapped at these virtual addresses.
> >  	 */
> > -	if (!efi_is_native()) {
> > +	if (!efi_is_native() || efi_enabled(EFI_OLD_MEMMAP)) {
> >  		efi_memmap_unmap();
> >  		clear_bit(EFI_RUNTIME_SERVICES, &efi.flags);
> >  		return;
> > -- 
> > 2.1.4
> > 
> 
> Suppose it has passed the test on your hardware:
> Acked-by: Dave Young <dyoung@redhat.com>
> 

Thanks Dave! Haha... yes.
I tested on qemu with OVMF

> Thanks
> Dave

Regards,
Sai

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#1643035 — Re: [PATCH v2] x86/efi: Disable runtime services on kexec kernel if booted with efi=old_map

Fromjoeyli <jlee@suse.com>
Date2017-05-17 09:30 +0200
SubjectRe: [PATCH v2] x86/efi: Disable runtime services on kexec kernel if booted with efi=old_map
Message-ID<tI1zb-8vR-5@gated-at.bofh.it>
In reply to#1642911
On Tue, May 16, 2017 at 06:14:23PM -0700, Sai Praneeth Prakhya wrote:
> From: Sai Praneeth <sai.praneeth.prakhya@intel.com>
> 
> Booting kexec kernel with "efi=old_map" in kernel command line hits
> kernel panic as shown below.
> 
> [0.001000] BUG: unable to handle kernel paging request at ffff88007fe78070
> [0.001000] IP: virt_efi_set_variable.part.7+0x63/0x1b0
> [0.001000] PGD 7ea28067
> [0.001000] PUD 7ea2b067
> [0.001000] PMD 7ea2d067
> [0.001000] PTE 0
> [0.001000]
> [0.001000] Oops: 0000 [#1] SMP
> [0.001000] Modules linked in:
> [0.001000] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.11.0-rc2-yocto-standard+ #229
> [0.001000] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 0.0.0 02/06/2015
> [0.001000] task: ffffffff82022500 task.stack: ffffffff82000000
> [0.001000] RIP: 0010:virt_efi_set_variable.part.7+0x63/0x1b0
> [0.001000] RSP: 0000:ffffffff82003dc0 EFLAGS: 00010246
> [0.001000] RAX: ffff88007fe78018 RBX: ffffffff82050300 RCX: 0000000000000007
> [0.001000] RDX: ffffffff82003e50 RSI: ffffffff82050300 RDI: ffffffff82050300
> [0.001000] RBP: ffffffff82003e08 R08: 0000000000000000 R09: 0000000000000000
> [0.001000] R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff82003e50
> [0.001000] R13: 0000000000000007 R14: 0000000000000246 R15: 0000000000000000
> [0.001000] FS:  0000000000000000(0000) GS:ffff88007fa00000(0000) knlGS:0000000000000000
> [0.001000] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [0.001000] CR2: ffff88007fe78070 CR3: 000000007da1d000 CR4: 00000000000006b0
> [0.001000] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> [0.001000] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> [0.001000] Call Trace:
> [0.001000]  virt_efi_set_variable+0x5d/0x70
> [0.001000]  efi_delete_dummy_variable+0x7a/0x80
> [0.001000]  efi_enter_virtual_mode+0x3f6/0x4a7
> [0.001000]  start_kernel+0x375/0x400
> [0.001000]  x86_64_start_reservations+0x2a/0x2c
> [0.001000]  x86_64_start_kernel+0x168/0x176
> [0.001000]  start_cpu+0x14/0x14
> [0.001000] Code: 04 b0 84 ff 80 3d c5 56 b3 00 00 4c 8b 44 24 08 75
> 6b 9c 41 5e 48 8b 05 9c 78 99 00 4d 89 c1 48 89 de 4d 89 f8 44 89 e9 4c
> 89 e2 <48> 8b 40 58 48 8b 78 58 e8 b0 2d 88 ff 48 c7 c6 b6 1d f4 81 4c
> [0.001000] RIP: virt_efi_set_variable.part.7+0x63/0x1b0 RSP: ffffffff82003dc0
> [0.001000] CR2: ffff88007fe78070
> [0.001000] ---[ end trace 0000000000000000 ]---
> [0.001000] Kernel panic - not syncing: Attempted to kill the idle task!
> [0.001000] ---[ end Kernel panic - not syncing: Attempted to kill the idle task!
> 
> [efi=old_map was never intended to work with kexec. The problem with
> using efi=old_map is that the virtual addresses are assigned from the
> memory region used by other kernel mappings; vmalloc() space.
> Potentially there could be collisions when booting kexec if something
> else is mapped at the virtual address we allocated for runtime service
> regions in the initial boot] - Matt Fleming
> 
> Since kexec was never intended to work with efi=old_map, disable
> runtime services in kexec if booted with efi=old_map, so that we don't
> panic.
> 
> Signed-off-by: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
> Cc: Borislav Petkov <bp@alien8.de>
> Cc: Ricardo Neri <ricardo.neri@intel.com>
> Cc: Matt Fleming <matt@codeblueprint.co.uk>
> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> Cc: Ravi Shankar <ravi.v.shankar@intel.com>
> Cc: Lee Chun-Yi <jlee@suse.com>
> Cc: Dave Young <dyoung@redhat.com>
> 
> Changes since v1:
> Don't fix the panic, because this was never intended to work.

I tested this patch on OVMF and Acer UEFI laptop. It works to me
for efi=old_map with crash kernel.

Tested-by: "Lee, Chun-Yi" <jlee@suse.com>

> ---
>  arch/x86/platform/efi/efi.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
> index 87835c97611f..627b7b86f369 100644
> --- a/arch/x86/platform/efi/efi.c
> +++ b/arch/x86/platform/efi/efi.c
> @@ -827,9 +827,11 @@ static void __init kexec_enter_virtual_mode(void)
>  
>  	/*
>  	 * We don't do virtual mode, since we don't do runtime services, on
> -	 * non-native EFI
> +	 * non-native EFI. With efi=old_map, we don't do runtime services in
> +	 * kexec kernel because in the initial boot something else might
> +	 * have been mapped at these virtual addresses.
>  	 */
> -	if (!efi_is_native()) {
> +	if (!efi_is_native() || efi_enabled(EFI_OLD_MEMMAP)) {
>  		efi_memmap_unmap();
>  		clear_bit(EFI_RUNTIME_SERVICES, &efi.flags);
>  		return;
> -- 
> 2.1.4
>

Thanks a lot!
Joey Lee

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#1650430 — Re: [PATCH v2] x86/efi: Disable runtime services on kexec kernel if booted with efi=old_map

FromMatt Fleming <matt@codeblueprint.co.uk>
Date2017-05-25 14:00 +0200
SubjectRe: [PATCH v2] x86/efi: Disable runtime services on kexec kernel if booted with efi=old_map
Message-ID<tKZAR-7IG-17@gated-at.bofh.it>
In reply to#1642911
On Tue, 16 May, at 06:14:23PM, Sai Praneeth Prakhya wrote:
> From: Sai Praneeth <sai.praneeth.prakhya@intel.com>
> 
> Booting kexec kernel with "efi=old_map" in kernel command line hits
> kernel panic as shown below.
> 
> [0.001000] BUG: unable to handle kernel paging request at ffff88007fe78070
> [0.001000] IP: virt_efi_set_variable.part.7+0x63/0x1b0
> [0.001000] PGD 7ea28067
> [0.001000] PUD 7ea2b067
> [0.001000] PMD 7ea2d067
> [0.001000] PTE 0
> [0.001000]
> [0.001000] Oops: 0000 [#1] SMP
> [0.001000] Modules linked in:
> [0.001000] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.11.0-rc2-yocto-standard+ #229
> [0.001000] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 0.0.0 02/06/2015
> [0.001000] task: ffffffff82022500 task.stack: ffffffff82000000
> [0.001000] RIP: 0010:virt_efi_set_variable.part.7+0x63/0x1b0
> [0.001000] RSP: 0000:ffffffff82003dc0 EFLAGS: 00010246
> [0.001000] RAX: ffff88007fe78018 RBX: ffffffff82050300 RCX: 0000000000000007
> [0.001000] RDX: ffffffff82003e50 RSI: ffffffff82050300 RDI: ffffffff82050300
> [0.001000] RBP: ffffffff82003e08 R08: 0000000000000000 R09: 0000000000000000
> [0.001000] R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff82003e50
> [0.001000] R13: 0000000000000007 R14: 0000000000000246 R15: 0000000000000000
> [0.001000] FS:  0000000000000000(0000) GS:ffff88007fa00000(0000) knlGS:0000000000000000
> [0.001000] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [0.001000] CR2: ffff88007fe78070 CR3: 000000007da1d000 CR4: 00000000000006b0
> [0.001000] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> [0.001000] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> [0.001000] Call Trace:
> [0.001000]  virt_efi_set_variable+0x5d/0x70
> [0.001000]  efi_delete_dummy_variable+0x7a/0x80
> [0.001000]  efi_enter_virtual_mode+0x3f6/0x4a7
> [0.001000]  start_kernel+0x375/0x400
> [0.001000]  x86_64_start_reservations+0x2a/0x2c
> [0.001000]  x86_64_start_kernel+0x168/0x176
> [0.001000]  start_cpu+0x14/0x14
> [0.001000] Code: 04 b0 84 ff 80 3d c5 56 b3 00 00 4c 8b 44 24 08 75
> 6b 9c 41 5e 48 8b 05 9c 78 99 00 4d 89 c1 48 89 de 4d 89 f8 44 89 e9 4c
> 89 e2 <48> 8b 40 58 48 8b 78 58 e8 b0 2d 88 ff 48 c7 c6 b6 1d f4 81 4c
> [0.001000] RIP: virt_efi_set_variable.part.7+0x63/0x1b0 RSP: ffffffff82003dc0
> [0.001000] CR2: ffff88007fe78070
> [0.001000] ---[ end trace 0000000000000000 ]---
> [0.001000] Kernel panic - not syncing: Attempted to kill the idle task!
> [0.001000] ---[ end Kernel panic - not syncing: Attempted to kill the idle task!
> 
> [efi=old_map was never intended to work with kexec. The problem with
> using efi=old_map is that the virtual addresses are assigned from the
> memory region used by other kernel mappings; vmalloc() space.
> Potentially there could be collisions when booting kexec if something
> else is mapped at the virtual address we allocated for runtime service
> regions in the initial boot] - Matt Fleming
> 
> Since kexec was never intended to work with efi=old_map, disable
> runtime services in kexec if booted with efi=old_map, so that we don't
> panic.
> 
> Signed-off-by: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
> Cc: Borislav Petkov <bp@alien8.de>
> Cc: Ricardo Neri <ricardo.neri@intel.com>
> Cc: Matt Fleming <matt@codeblueprint.co.uk>
> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> Cc: Ravi Shankar <ravi.v.shankar@intel.com>
> Cc: Lee Chun-Yi <jlee@suse.com>
> Cc: Dave Young <dyoung@redhat.com>
> 
> Changes since v1:
> Don't fix the panic, because this was never intended to work.
> ---
>  arch/x86/platform/efi/efi.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)

Thanks Sai, applied to the urgent branch.

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