[Xen-ia64-devel] [patch] alloc_page_dir() should return a virtual address

[Jes Sorensen <jes@xxxxxxx>]

Hi,

I sent this patch to Alex last week, but it didn't make it onto the list
because it's wrongly configured, so here we go again.

I know that this patch is causing problems on ZX1, but I have looked at
it over and over again and I feel pretty certain it is correct. In fact
I cannot understand that Xen could boot on any ia64 platform prior to
this at all.

I would be very interested in hearing how this patch affects other
platforms such as DIG and Fujitsu's machines (if they are not DIG :)

Any input or comments on this is most welcome - if you think I am wrong
about this patch, please tell me, I really want to understand why this
worked in the past.

Thanks,
Jes

alloc_dir_page() must return a virtual address so it can handle being
passed to the p*d_populate() functions which do a __pa() on the address
before sticking them into the page tables.

To match this it is also necessary to correctly check the faulting
address for being in the virtual frame table range, otherwise page
faults for this space weren't being served at all.

This could probably be done more efficiently, but for now I think it's
better to keep the code explicit.

Signed-off-by: Jes Sorensen <jes@xxxxxxx>

diff -r 3e4fa8b5b245 xen/arch/ia64/xen/ivt.S
--- a/xen/arch/ia64/xen/ivt.S   Tue Sep 12 11:43:22 2006 -0600
+++ b/xen/arch/ia64/xen/ivt.S   Wed Sep 20 14:56:37 2006 +0200
@@ -542,8 +542,16 @@ late_alt_dtlb_miss:
        ;;
 #ifdef CONFIG_VIRTUAL_FRAME_TABLE
        shr r22=r16,56          // Test for the address of virtual frame_table
+#if 1
+       mov r23=VIRT_FRAME_TABLE_ADDR>>56
+       ;;
+       xor r23=r22,r23
+       ;;
+       cmp.eq p8,p0=r23,r0
+#else
        ;;
        cmp.eq p8,p0=((VIRT_FRAME_TABLE_ADDR>>56)&0xff)-0x100,r22
+#endif
 (p8)   br.cond.sptk frametable_miss ;;
 #endif
        // If it is not a Xen address, handle it via page_fault.
diff -r 3e4fa8b5b245 xen/arch/ia64/xen/xenmem.c
--- a/xen/arch/ia64/xen/xenmem.c        Tue Sep 12 11:43:22 2006 -0600
+++ b/xen/arch/ia64/xen/xenmem.c        Wed Sep 20 17:14:01 2006 +0200
@@ -76,13 +76,13 @@ alloc_dir_page(void)
 alloc_dir_page(void)
 {
        unsigned long mfn = alloc_boot_pages(1, 1);
-       unsigned long dir;
+       unsigned char *virtual;
        if (!mfn)
                panic("Not enough memory for virtual frame table!\n");
        ++table_size;
-       dir = mfn << PAGE_SHIFT;
-       memset(__va(dir), 0, PAGE_SIZE);
-       return (void *)dir;
+       virtual = __va(mfn << PAGE_SHIFT);
+       memset(virtual, 0, PAGE_SIZE);
+       return virtual;
 }
 
 static inline unsigned long

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