x86/gart: Rewrite early_gart_iommu_check() comment
Borislav Petkov
maintainerPATCH 1/1 x86/gart: Rewrite early_gart_iommu_check() comment
From: Borislav Petkov <[email protected]>
... to actually explain what the function is trying to do.
Reported-by Mike Rapoport <[email protected]>
Signed-off-by Borislav Petkov <[email protected]>
--- arch/x86/kernel/aperture_64.c | 25 +++++++++++++++---------- 1 file changed, 15 insertions(+), 10 deletions(-)
arch/x86/kernel/aperture_64.c +15 -10
@@ -264,18 +264,23 @@ static int __init parse_gart_mem(char *p) }early_param ("gart_fix_e820" , parse_gart_mem); +/* +* With kexec/kdump, if the first kernel doesn't shutdown the GART and the +* second kernel allocates a different GART region, there might be two +* overlapping GART regions present: +* +* - the first still used by the GART initialized in the first kernel. +* - (sub-)set of it used as normal RAM by the second kernel. +* +* which leads to memory corruptions and a kernel panic eventually. +* +* This can also happen if the BIOS has forgotten to mark the GART region +* as reserved. +* +* Try to update the e820 map to mark that new region as reserved. +*/ void __init early_gart_iommu_check (void ) { -/* -* in case it is enabled before, esp for kexec/kdump, -* previous kernel already enable that. memset called -* by allocate_aperture/__alloc_bootmem_nopanic cause restart. -* or second kernel have different position for GART hole. and new -* kernel could use hole as RAM that is still used by GART set by -* first kernel -* or BIOS forget to put that in reserved. -* try to update e820 to make that region as reserved. -*/ u32 agp_aper_order =0 ;int i, fix, slot, valid_agp =0 ;u32 ctl;
Signature · 1 line
2.19.1
Quoted 6 lines · Borislav Petkov
From: Borislav Petkov <[email protected]>
... to actually explain what the function is trying to do.
Reported-by Mike Rapoport <[email protected]>Signed-off-by Borislav Petkov <[email protected]>
Reviewed-by Thomas Gleixner <[email protected]>
tip-bot for Borislav Petkov
merge botx86/gart: Rewrite early_gart_iommu_check() comment
Commit-ID: 59d130cc9b92b92feaada94a0802fa747038d17f Gitweb: https://git.kernel.org/tip/59d130cc9b92b92feaada94a0802fa747038d17f Author: Borislav Petkov <[email protected]> AuthorDate: Thu, 1 Nov 2018 16:24:43 +0100 Committer: Borislav Petkov <[email protected]> CommitDate: Mon, 5 Nov 2018 14:35:10 +0100
x86/gart: Rewrite early_gart_iommu_check() comment
... to actually explain what the function is trying to do.
Reported-by Mike Rapoport <[email protected]>
Signed-off-by Borislav Petkov <[email protected]>
Reviewed-by Thomas Gleixner <[email protected]>
Cc <[email protected]>
--- arch/x86/kernel/aperture_64.c | 25 +++++++++++++++---------- 1 file changed, 15 insertions(+), 10 deletions(-)
arch/x86/kernel/aperture_64.c +15 -10
@@ -264,18 +264,23 @@ static int __init parse_gart_mem(char *p) }early_param ("gart_fix_e820" , parse_gart_mem); +/* +* With kexec/kdump, if the first kernel doesn't shutdown the GART and the +* second kernel allocates a different GART region, there might be two +* overlapping GART regions present: +* +* - the first still used by the GART initialized in the first kernel. +* - (sub-)set of it used as normal RAM by the second kernel. +* +* which leads to memory corruptions and a kernel panic eventually. +* +* This can also happen if the BIOS has forgotten to mark the GART region +* as reserved. +* +* Try to update the e820 map to mark that new region as reserved. +*/ void __init early_gart_iommu_check (void ) { -/* -* in case it is enabled before, esp for kexec/kdump, -* previous kernel already enable that. memset called -* by allocate_aperture/__alloc_bootmem_nopanic cause restart. -* or second kernel have different position for GART hole. and new -* kernel could use hole as RAM that is still used by GART set by -* first kernel -* or BIOS forget to put that in reserved. -* try to update e820 to make that region as reserved. -*/ u32 agp_aper_order =0 ;int i, fix, slot, valid_agp =0 ;u32 ctl;
Quoted 15 lines · Borislav Petkov
From: Borislav Petkov <[email protected]>
... to actually explain what the function is trying to do.
Reported-by Mike Rapoport <[email protected]>Signed-off-by Borislav Petkov <[email protected]>--- arch/x86/kernel/aperture_64.c | 25 +++++++++++++++---------- 1 file changed, 15 insertions(+), 10 deletions(-)arch/x86/kernel/aperture_64.c +0
-0
arch/x86/kernel/aperture_64.c static int __init parse_gart_mem(char *p) · line 270
Quoted 7 lines
arch/x86/kernel/aperture_64.c +4
-0@@ -264,18 +264,23 @@ static int __init parse_gart_mem(char *p) }early_param ("gart_fix_e820" , parse_gart_mem); +/* +* With kexec/kdump, if the first kernel doesn't shutdown the GART and the +* second kernel allocates a different GART region, there might be two +* overlapping GART regions present:
s/shutdown
/shut down
Thanks,
Ingo
Borislav Petkov
maintainerQuoted 2 lines · Ingo Molnar
s/shutdown
/shut down
Fixed.
Thx.
Signature · 4 lines
Regards/Gruss,
Boris.
Good mailing practices for 400: avoid top-posting and trim the reply.tip-bot for Borislav Petkov
merge botx86/gart: Rewrite early_gart_iommu_check() comment
Commit-ID: 63ecd3b13d5cf07959a2315ec62a7c62e20df114 Gitweb: https://git.kernel.org/tip/63ecd3b13d5cf07959a2315ec62a7c62e20df114 Author: Borislav Petkov <[email protected]> AuthorDate: Thu, 1 Nov 2018 16:24:43 +0100 Committer: Borislav Petkov <[email protected]> CommitDate: Mon, 5 Nov 2018 21:18:31 +0100
x86/gart: Rewrite early_gart_iommu_check() comment
... to actually explain what the function is trying to do.
Reported-by Mike Rapoport <[email protected]>
Signed-off-by Borislav Petkov <[email protected]>
Reviewed-by Thomas Gleixner <[email protected]>
Cc <[email protected]>
--- arch/x86/kernel/aperture_64.c | 25 +++++++++++++++---------- 1 file changed, 15 insertions(+), 10 deletions(-)
arch/x86/kernel/aperture_64.c +15 -10
@@ -264,18 +264,23 @@ static int __init parse_gart_mem(char *p) }early_param ("gart_fix_e820" , parse_gart_mem); +/* +* With kexec/kdump, if the first kernel doesn't shut down the GART and the +* second kernel allocates a different GART region, there might be two +* overlapping GART regions present: +* +* - the first still used by the GART initialized in the first kernel. +* - (sub-)set of it used as normal RAM by the second kernel. +* +* which leads to memory corruptions and a kernel panic eventually. +* +* This can also happen if the BIOS has forgotten to mark the GART region +* as reserved. +* +* Try to update the e820 map to mark that new region as reserved. +*/ void __init early_gart_iommu_check (void ) { -/* -* in case it is enabled before, esp for kexec/kdump, -* previous kernel already enable that. memset called -* by allocate_aperture/__alloc_bootmem_nopanic cause restart. -* or second kernel have different position for GART hole. and new -* kernel could use hole as RAM that is still used by GART set by -* first kernel -* or BIOS forget to put that in reserved. -* try to update e820 to make that region as reserved. -*/ u32 agp_aper_order =0 ;int i, fix, slot, valid_agp =0 ;u32 ctl;