Re: [PATCH v3 02/11] x86/kexec: Add extra pointers to transition page table PGD, PUD, PMD and PTE
On 04.01.13 at 18:25, Daniel Kiper daniel.ki...@oracle.com wrote: Right, so where is virtual mapping of control page established? I could not find relevant code in SLES kernel which does that. In the hypervisor (xen/arch/x86/machine_kexec.c:machine_kexec_load()). xen/arch/x86/machine_kexec.c:machine_kexec() then simply uses image-page_list[1]. Jan ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
Re: [PATCH v3 02/11] x86/kexec: Add extra pointers to transition page table PGD, PUD, PMD and PTE
On Mon, Jan 07, 2013 at 09:48:20AM +, Jan Beulich wrote: On 04.01.13 at 18:25, Daniel Kiper daniel.ki...@oracle.com wrote: Right, so where is virtual mapping of control page established? I could not find relevant code in SLES kernel which does that. In the hypervisor (xen/arch/x86/machine_kexec.c:machine_kexec_load()). xen/arch/x86/machine_kexec.c:machine_kexec() then simply uses image-page_list[1]. This (xen/arch/x86/machine_kexec.c:machine_kexec_load()) maps relevant page (allocated earlier by dom0) in hypervisor fixmap area. However, it does not make relevant mapping in transition page table which leads to crash when %cr3 is switched from Xen page table to transition page table. Daniel ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
Re: [PATCH v3 02/11] x86/kexec: Add extra pointers to transition page table PGD, PUD, PMD and PTE
On 07.01.13 at 13:52, Daniel Kiper daniel.ki...@oracle.com wrote: On Mon, Jan 07, 2013 at 09:48:20AM +, Jan Beulich wrote: On 04.01.13 at 18:25, Daniel Kiper daniel.ki...@oracle.com wrote: Right, so where is virtual mapping of control page established? I could not find relevant code in SLES kernel which does that. In the hypervisor (xen/arch/x86/machine_kexec.c:machine_kexec_load()). xen/arch/x86/machine_kexec.c:machine_kexec() then simply uses image-page_list[1]. This (xen/arch/x86/machine_kexec.c:machine_kexec_load()) maps relevant page (allocated earlier by dom0) in hypervisor fixmap area. However, it does not make relevant mapping in transition page table which leads to crash when %cr3 is switched from Xen page table to transition page table. That indeed could explain _random_ failures - the fixmap entries get created with _PAGE_GLOBAL set, i.e. don't get flushed with the CR3 write unless CR4.PGE is clear. And I don't see how your allocation of intermediate page tables would help: You wouldn't know where the mapping of the control page lives until you're actually in the early relocate_kernel code. Or was it that what distinguishes your cloned code from the native original? Jan ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
Re: [PATCH v3 02/11] x86/kexec: Add extra pointers to transition page table PGD, PUD, PMD and PTE
On Fri, Dec 28, 2012 at 01:59:27PM +0100, Borislav Petkov wrote: On Thu, Dec 27, 2012 at 03:19:24PM -0800, Daniel Kiper wrote: Hmm... this code is being redone at the moment... this might conflict. Is this available somewhere? May I have a look at it? http://marc.info/?l=linux-kernelm=135581534620383 The for-x86-boot-v7 and -v8 branches. HTH. Thanks. Daniel ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
Re: [PATCH v3 02/11] x86/kexec: Add extra pointers to transition page table PGD, PUD, PMD and PTE
On Thu, Jan 03, 2013 at 09:34:55AM +, Jan Beulich wrote: On 27.12.12 at 03:18, Daniel Kiper daniel.ki...@oracle.com wrote: Some implementations (e.g. Xen PVOPS) could not use part of identity page table to construct transition page table. It means that they require separate PUDs, PMDs and PTEs for virtual and physical (identity) mapping. To satisfy that requirement add extra pointer to PGD, PUD, PMD and PTE and align existing code. So you keep posting this despite it having got pointed out on each earlier submission that this is unnecessary, proven by the fact that the non-pvops Xen kernels can get away without it. Why? Sorry but I forgot to reply for your email last time. I am still not convinced. I have tested SUSE kernel itself and it does not work. Maybe I missed something but... Please check arch/x86/kernel/machine_kexec_64.c:init_transition_pgtable() I can see: vaddr = (unsigned long)relocate_kernel; and later: pgd += pgd_index(vaddr); ... It is wrong. relocate_kernel() virtual address in Xen is different than its virtual address in Linux Kernel. That is why transition page table could not be established in Linux Kernel and so on... How does this work in SUSE? I do not have an idea. I am happy to fix that but whatever fix for it is I would like to be sure that it works. Daniel ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
Re: [PATCH v3 02/11] x86/kexec: Add extra pointers to transition page table PGD, PUD, PMD and PTE
On 04.01.13 at 16:15, Daniel Kiper daniel.ki...@oracle.com wrote: On Thu, Jan 03, 2013 at 09:34:55AM +, Jan Beulich wrote: On 27.12.12 at 03:18, Daniel Kiper daniel.ki...@oracle.com wrote: Some implementations (e.g. Xen PVOPS) could not use part of identity page table to construct transition page table. It means that they require separate PUDs, PMDs and PTEs for virtual and physical (identity) mapping. To satisfy that requirement add extra pointer to PGD, PUD, PMD and PTE and align existing code. So you keep posting this despite it having got pointed out on each earlier submission that this is unnecessary, proven by the fact that the non-pvops Xen kernels can get away without it. Why? Sorry but I forgot to reply for your email last time. I am still not convinced. I have tested SUSE kernel itself and it does not work. Maybe I missed something but... Please check arch/x86/kernel/machine_kexec_64.c:init_transition_pgtable() I can see: vaddr = (unsigned long)relocate_kernel; and later: pgd += pgd_index(vaddr); ... I think that mapping is simply irrelevant, as the code at relocate_kernel gets copied to the control page and invoked there (other than in the native case, where relocate_kernel() gets invoked directly). Jan It is wrong. relocate_kernel() virtual address in Xen is different than its virtual address in Linux Kernel. That is why transition page table could not be established in Linux Kernel and so on... How does this work in SUSE? I do not have an idea. I am happy to fix that but whatever fix for it is I would like to be sure that it works. Daniel ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
Re: [PATCH v3 02/11] x86/kexec: Add extra pointers to transition page table PGD, PUD, PMD and PTE
On Fri, Jan 04, 2013 at 04:12:32PM +, Jan Beulich wrote: On 04.01.13 at 16:15, Daniel Kiper daniel.ki...@oracle.com wrote: On Thu, Jan 03, 2013 at 09:34:55AM +, Jan Beulich wrote: On 27.12.12 at 03:18, Daniel Kiper daniel.ki...@oracle.com wrote: Some implementations (e.g. Xen PVOPS) could not use part of identity page table to construct transition page table. It means that they require separate PUDs, PMDs and PTEs for virtual and physical (identity) mapping. To satisfy that requirement add extra pointer to PGD, PUD, PMD and PTE and align existing code. So you keep posting this despite it having got pointed out on each earlier submission that this is unnecessary, proven by the fact that the non-pvops Xen kernels can get away without it. Why? Sorry but I forgot to reply for your email last time. I am still not convinced. I have tested SUSE kernel itself and it does not work. Maybe I missed something but... Please check arch/x86/kernel/machine_kexec_64.c:init_transition_pgtable() I can see: vaddr = (unsigned long)relocate_kernel; and later: pgd += pgd_index(vaddr); ... I think that mapping is simply irrelevant, as the code at relocate_kernel gets copied to the control page and invoked there (other than in the native case, where relocate_kernel() gets invoked directly). Right, so where is virtual mapping of control page established? I could not find relevant code in SLES kernel which does that. Daniel ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
Re: [PATCH v3 02/11] x86/kexec: Add extra pointers to transition page table PGD, PUD, PMD and PTE
On 27.12.12 at 03:18, Daniel Kiper daniel.ki...@oracle.com wrote: Some implementations (e.g. Xen PVOPS) could not use part of identity page table to construct transition page table. It means that they require separate PUDs, PMDs and PTEs for virtual and physical (identity) mapping. To satisfy that requirement add extra pointer to PGD, PUD, PMD and PTE and align existing code. So you keep posting this despite it having got pointed out on each earlier submission that this is unnecessary, proven by the fact that the non-pvops Xen kernels can get away without it. Why? Jan ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
Re: [PATCH v3 02/11] x86/kexec: Add extra pointers to transition page table PGD, PUD, PMD and PTE
On Thu, Dec 27, 2012 at 03:19:24PM -0800, Daniel Kiper wrote: Hmm... this code is being redone at the moment... this might conflict. Is this available somewhere? May I have a look at it? http://marc.info/?l=linux-kernelm=135581534620383 The for-x86-boot-v7 and -v8 branches. HTH. -- Regards/Gruss, Boris. ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
Re: [PATCH v3 02/11] x86/kexec: Add extra pointers to transition page table PGD, PUD, PMD and PTE
Hmm... this code is being redone at the moment... this might conflict. Is this available somewhere? May I have a look at it? Daniel PS I am on holiday until 02/01/2013 and I could not have access to my email box. Please be patient. At worst case I will send reply when I will be back at office. ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
Re: [PATCH v3 02/11] x86/kexec: Add extra pointers to transition page table PGD, PUD, PMD and PTE
Hmm... this code is being redone at the moment... this might conflict.
Daniel Kiper daniel.ki...@oracle.com wrote:
Some implementations (e.g. Xen PVOPS) could not use part of identity
page table
to construct transition page table. It means that they require separate
PUDs,
PMDs and PTEs for virtual and physical (identity) mapping. To satisfy
that
requirement add extra pointer to PGD, PUD, PMD and PTE and align
existing code.
Signed-off-by: Daniel Kiper daniel.ki...@oracle.com
---
arch/x86/include/asm/kexec.h | 10 +++---
arch/x86/kernel/machine_kexec_64.c | 12 ++--
2 files changed, 13 insertions(+), 9 deletions(-)
diff --git a/arch/x86/include/asm/kexec.h
b/arch/x86/include/asm/kexec.h
index 6080d26..cedd204 100644
--- a/arch/x86/include/asm/kexec.h
+++ b/arch/x86/include/asm/kexec.h
@@ -157,9 +157,13 @@ struct kimage_arch {
};
#else
struct kimage_arch {
- pud_t *pud;
- pmd_t *pmd;
- pte_t *pte;
+ pgd_t *pgd;
+ pud_t *pud0;
+ pud_t *pud1;
+ pmd_t *pmd0;
+ pmd_t *pmd1;
+ pte_t *pte0;
+ pte_t *pte1;
};
#endif
diff --git a/arch/x86/kernel/machine_kexec_64.c
b/arch/x86/kernel/machine_kexec_64.c
index b3ea9db..976e54b 100644
--- a/arch/x86/kernel/machine_kexec_64.c
+++ b/arch/x86/kernel/machine_kexec_64.c
@@ -137,9 +137,9 @@ out:
static void free_transition_pgtable(struct kimage *image)
{
- free_page((unsigned long)image-arch.pud);
- free_page((unsigned long)image-arch.pmd);
- free_page((unsigned long)image-arch.pte);
+ free_page((unsigned long)image-arch.pud0);
+ free_page((unsigned long)image-arch.pmd0);
+ free_page((unsigned long)image-arch.pte0);
}
static int init_transition_pgtable(struct kimage *image, pgd_t *pgd)
@@ -157,7 +157,7 @@ static int init_transition_pgtable(struct kimage
*image, pgd_t *pgd)
pud = (pud_t *)get_zeroed_page(GFP_KERNEL);
if (!pud)
goto err;
- image-arch.pud = pud;
+ image-arch.pud0 = pud;
set_pgd(pgd, __pgd(__pa(pud) | _KERNPG_TABLE));
}
pud = pud_offset(pgd, vaddr);
@@ -165,7 +165,7 @@ static int init_transition_pgtable(struct kimage
*image, pgd_t *pgd)
pmd = (pmd_t *)get_zeroed_page(GFP_KERNEL);
if (!pmd)
goto err;
- image-arch.pmd = pmd;
+ image-arch.pmd0 = pmd;
set_pud(pud, __pud(__pa(pmd) | _KERNPG_TABLE));
}
pmd = pmd_offset(pud, vaddr);
@@ -173,7 +173,7 @@ static int init_transition_pgtable(struct kimage
*image, pgd_t *pgd)
pte = (pte_t *)get_zeroed_page(GFP_KERNEL);
if (!pte)
goto err;
- image-arch.pte = pte;
+ image-arch.pte0 = pte;
set_pmd(pmd, __pmd(__pa(pte) | _KERNPG_TABLE));
}
pte = pte_offset_kernel(pmd, vaddr);
--
Sent from my mobile phone. Please excuse brevity and lack of formatting.
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