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[Xen-devel] Re: [git pull] xen, x86 fixes

To: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
Subject: [Xen-devel] Re: [git pull] xen, x86 fixes
From: Ingo Molnar <mingo@xxxxxxx>
Date: Tue, 24 Jun 2008 17:18:12 +0200
Cc: Adrian Bunk <bunk@xxxxxxxxxx>, Rusty Russell <rusty@xxxxxxxxxxxxxxx>, the arch/x86 maintainers <x86@xxxxxxxxxx>, linux-kernel@xxxxxxxxxxxxxxx, chrisw@xxxxxxxxxxxx, xen-devel@xxxxxxxxxxxxxxxxxxx, Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
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* Jeremy Fitzhardinge <jeremy@xxxxxxxx> wrote:

> Bringing that patch over into .26 would be the easiest fix.  It's 
> effectively a bugfix because non-PAE Xen is broken and unusable 
> anyway.
>
> Alternatively, I can easily put a little patch together to use the 
> right accessors that will compile in non-PAE.

that patch has been in testing since early May so we can put it into 
v2.6.26 - and as you say non-PAE paravirt guest support in Xen is 
deprecated and rarely used/tested.

Linus,

Please pull the latest x86 fixes git tree from:

   git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip.git 
x86-fixes-for-linus

which includes a cherry-pick of this one Xen commit from Jeremy - this 
fixes the build error reported by Adrian Bunk.

( alternatively we could do just the arch/x86/xen/Kconfig bit too but i 
  think we should just take this one as it touches Xen code only. )

Thanks,

        Ingo

------------------>
Jeremy Fitzhardinge (1):
      xen: remove support for non-PAE 32-bit

 arch/x86/xen/Kconfig       |    2 +-
 arch/x86/xen/enlighten.c   |   51 +++++++++++++++----------------------------
 arch/x86/xen/mmu.c         |   19 +--------------
 arch/x86/xen/mmu.h         |   24 +++++---------------
 arch/x86/xen/xen-head.S    |    4 ---
 include/asm-x86/xen/page.h |    4 ---
 6 files changed, 27 insertions(+), 77 deletions(-)

diff --git a/arch/x86/xen/Kconfig b/arch/x86/xen/Kconfig
index 2e641be..525b108 100644
--- a/arch/x86/xen/Kconfig
+++ b/arch/x86/xen/Kconfig
@@ -6,7 +6,7 @@ config XEN
        bool "Xen guest support"
        select PARAVIRT
        depends on X86_32
-       depends on X86_CMPXCHG && X86_TSC && !(X86_VISWS || X86_VOYAGER)
+       depends on X86_CMPXCHG && X86_TSC && X86_PAE && !(X86_VISWS || 
X86_VOYAGER)
        help
          This is the Linux Xen port.  Enabling this will allow the
          kernel to boot in a paravirtualized environment under the
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index c048de3..f09c1c6 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -785,38 +785,35 @@ static __init void xen_set_pte_init(pte_t *ptep, pte_t 
pte)
 static __init void xen_pagetable_setup_start(pgd_t *base)
 {
        pgd_t *xen_pgd = (pgd_t *)xen_start_info->pt_base;
+       int i;
 
        /* special set_pte for pagetable initialization */
        pv_mmu_ops.set_pte = xen_set_pte_init;
 
        init_mm.pgd = base;
        /*
-        * copy top-level of Xen-supplied pagetable into place.  For
-        * !PAE we can use this as-is, but for PAE it is a stand-in
-        * while we copy the pmd pages.
+        * copy top-level of Xen-supplied pagetable into place.  This
+        * is a stand-in while we copy the pmd pages.
         */
        memcpy(base, xen_pgd, PTRS_PER_PGD * sizeof(pgd_t));
 
-       if (PTRS_PER_PMD > 1) {
-               int i;
-               /*
-                * For PAE, need to allocate new pmds, rather than
-                * share Xen's, since Xen doesn't like pmd's being
-                * shared between address spaces.
-                */
-               for (i = 0; i < PTRS_PER_PGD; i++) {
-                       if (pgd_val_ma(xen_pgd[i]) & _PAGE_PRESENT) {
-                               pmd_t *pmd = (pmd_t 
*)alloc_bootmem_low_pages(PAGE_SIZE);
+       /*
+        * For PAE, need to allocate new pmds, rather than
+        * share Xen's, since Xen doesn't like pmd's being
+        * shared between address spaces.
+        */
+       for (i = 0; i < PTRS_PER_PGD; i++) {
+               if (pgd_val_ma(xen_pgd[i]) & _PAGE_PRESENT) {
+                       pmd_t *pmd = (pmd_t 
*)alloc_bootmem_low_pages(PAGE_SIZE);
 
-                               memcpy(pmd, (void *)pgd_page_vaddr(xen_pgd[i]),
-                                      PAGE_SIZE);
+                       memcpy(pmd, (void *)pgd_page_vaddr(xen_pgd[i]),
+                              PAGE_SIZE);
 
-                               make_lowmem_page_readonly(pmd);
+                       make_lowmem_page_readonly(pmd);
 
-                               set_pgd(&base[i], __pgd(1 + __pa(pmd)));
-                       } else
-                               pgd_clear(&base[i]);
-               }
+                       set_pgd(&base[i], __pgd(1 + __pa(pmd)));
+               } else
+                       pgd_clear(&base[i]);
        }
 
        /* make sure zero_page is mapped RO so we can use it in pagetables */
@@ -873,17 +870,7 @@ static __init void xen_pagetable_setup_done(pgd_t *base)
 
        /* Actually pin the pagetable down, but we can't set PG_pinned
           yet because the page structures don't exist yet. */
-       {
-               unsigned level;
-
-#ifdef CONFIG_X86_PAE
-               level = MMUEXT_PIN_L3_TABLE;
-#else
-               level = MMUEXT_PIN_L2_TABLE;
-#endif
-
-               pin_pagetable_pfn(level, PFN_DOWN(__pa(base)));
-       }
+       pin_pagetable_pfn(MMUEXT_PIN_L3_TABLE, PFN_DOWN(__pa(base)));
 }
 
 /* This is called once we have the cpu_possible_map */
@@ -1093,7 +1080,6 @@ static const struct pv_mmu_ops xen_mmu_ops __initdata = {
        .make_pte = xen_make_pte,
        .make_pgd = xen_make_pgd,
 
-#ifdef CONFIG_X86_PAE
        .set_pte_atomic = xen_set_pte_atomic,
        .set_pte_present = xen_set_pte_at,
        .set_pud = xen_set_pud,
@@ -1102,7 +1088,6 @@ static const struct pv_mmu_ops xen_mmu_ops __initdata = {
 
        .make_pmd = xen_make_pmd,
        .pmd_val = xen_pmd_val,
-#endif /* PAE */
 
        .activate_mm = xen_activate_mm,
        .dup_mmap = xen_dup_mmap,
diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index 265601d..df40bf7 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -228,7 +228,7 @@ pmdval_t xen_pmd_val(pmd_t pmd)
 {
        return pte_mfn_to_pfn(pmd.pmd);
 }
-#ifdef CONFIG_X86_PAE
+
 void xen_set_pud(pud_t *ptr, pud_t val)
 {
        struct multicall_space mcs;
@@ -276,12 +276,6 @@ pmd_t xen_make_pmd(pmdval_t pmd)
        pmd = pte_pfn_to_mfn(pmd);
        return native_make_pmd(pmd);
 }
-#else  /* !PAE */
-void xen_set_pte(pte_t *ptep, pte_t pte)
-{
-       *ptep = pte;
-}
-#endif /* CONFIG_X86_PAE */
 
 /*
   (Yet another) pagetable walker.  This one is intended for pinning a
@@ -434,8 +428,6 @@ static int pin_page(struct page *page, enum pt_level level)
    read-only, and can be pinned. */
 void xen_pgd_pin(pgd_t *pgd)
 {
-       unsigned level;
-
        xen_mc_batch();
 
        if (pgd_walk(pgd, pin_page, TASK_SIZE)) {
@@ -445,14 +437,7 @@ void xen_pgd_pin(pgd_t *pgd)
                xen_mc_batch();
        }
 
-#ifdef CONFIG_X86_PAE
-       level = MMUEXT_PIN_L3_TABLE;
-#else
-       level = MMUEXT_PIN_L2_TABLE;
-#endif
-
-       xen_do_pin(level, PFN_DOWN(__pa(pgd)));
-
+       xen_do_pin(MMUEXT_PIN_L3_TABLE, PFN_DOWN(__pa(pgd)));
        xen_mc_issue(0);
 }
 
diff --git a/arch/x86/xen/mmu.h b/arch/x86/xen/mmu.h
index b5e189b..5fe961c 100644
--- a/arch/x86/xen/mmu.h
+++ b/arch/x86/xen/mmu.h
@@ -37,14 +37,13 @@ void xen_exit_mmap(struct mm_struct *mm);
 void xen_pgd_pin(pgd_t *pgd);
 //void xen_pgd_unpin(pgd_t *pgd);
 
-#ifdef CONFIG_X86_PAE
-unsigned long long xen_pte_val(pte_t);
-unsigned long long xen_pmd_val(pmd_t);
-unsigned long long xen_pgd_val(pgd_t);
+pteval_t xen_pte_val(pte_t);
+pmdval_t xen_pmd_val(pmd_t);
+pgdval_t xen_pgd_val(pgd_t);
 
-pte_t xen_make_pte(unsigned long long);
-pmd_t xen_make_pmd(unsigned long long);
-pgd_t xen_make_pgd(unsigned long long);
+pte_t xen_make_pte(pteval_t);
+pmd_t xen_make_pmd(pmdval_t);
+pgd_t xen_make_pgd(pgdval_t);
 
 void xen_set_pte_at(struct mm_struct *mm, unsigned long addr,
                    pte_t *ptep, pte_t pteval);
@@ -53,15 +52,4 @@ void xen_set_pud(pud_t *ptr, pud_t val);
 void xen_pte_clear(struct mm_struct *mm, unsigned long addr, pte_t *ptep);
 void xen_pmd_clear(pmd_t *pmdp);
 
-
-#else
-unsigned long xen_pte_val(pte_t);
-unsigned long xen_pmd_val(pmd_t);
-unsigned long xen_pgd_val(pgd_t);
-
-pte_t xen_make_pte(unsigned long);
-pmd_t xen_make_pmd(unsigned long);
-pgd_t xen_make_pgd(unsigned long);
-#endif
-
 #endif /* _XEN_MMU_H */
diff --git a/arch/x86/xen/xen-head.S b/arch/x86/xen/xen-head.S
index 3175e97..6ec3b4f 100644
--- a/arch/x86/xen/xen-head.S
+++ b/arch/x86/xen/xen-head.S
@@ -30,11 +30,7 @@ ENTRY(hypercall_page)
        ELFNOTE(Xen, XEN_ELFNOTE_ENTRY,          .long  startup_xen)
        ELFNOTE(Xen, XEN_ELFNOTE_HYPERCALL_PAGE, .long  hypercall_page)
        ELFNOTE(Xen, XEN_ELFNOTE_FEATURES,       .asciz 
"!writable_page_tables|pae_pgdir_above_4gb")
-#ifdef CONFIG_X86_PAE
        ELFNOTE(Xen, XEN_ELFNOTE_PAE_MODE,       .asciz "yes")
-#else
-       ELFNOTE(Xen, XEN_ELFNOTE_PAE_MODE,       .asciz "no")
-#endif
        ELFNOTE(Xen, XEN_ELFNOTE_LOADER,         .asciz "generic")
 
 #endif /*CONFIG_XEN */
diff --git a/include/asm-x86/xen/page.h b/include/asm-x86/xen/page.h
index baf3a4d..e11f240 100644
--- a/include/asm-x86/xen/page.h
+++ b/include/asm-x86/xen/page.h
@@ -150,13 +150,9 @@ static inline pte_t __pte_ma(pteval_t x)
        return (pte_t) { .pte = x };
 }
 
-#ifdef CONFIG_X86_PAE
 #define pmd_val_ma(v) ((v).pmd)
 #define pud_val_ma(v) ((v).pgd.pgd)
 #define __pmd_ma(x)    ((pmd_t) { (x) } )
-#else  /* !X86_PAE */
-#define pmd_val_ma(v)  ((v).pud.pgd.pgd)
-#endif /* CONFIG_X86_PAE */
 
 #define pgd_val_ma(x)  ((x).pgd)
 

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