RE: [Xen-devel] [patch] (resend) mask out nx bits when calculatingpfn/mfn

["Nakajima, Jun" <jun.nakajima@xxxxxxxxx>]

But did you really see the NX bit? I think that (NX bit) would be a good
catch and it explains several failures of device drivers.  We should fix
the creator of the pte (by __supported_pte_mask), not the consumer of
it.

We also need to fix Xen because Xen should not reject the request just
because it has the NX bit on.

Jun
---
Intel Open Source Technology Center 

-----Original Message-----
From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
[mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Scott Parish
Sent: Tuesday, June 07, 2005 9:00 AM
To: xen-devel@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Xen-devel] [patch] (resend) mask out nx bits when
calculatingpfn/mfn

Please ignore the first patch, it had a messed up macro.

sRp

On Tue, Jun 07, 2005 at 03:52:50PM +0000, Scott Parish wrote:

> This patch fixes a problem where it was possible (and seen) for the
> NX bit to not be masked out when calculating a pfn or mfn.
> 
> 
> sRp
> 
> -- 
> Scott Parish
> Signed-off-by: srparish@xxxxxxxxxx

> diff -rN -u -p
old-xen-64-4/linux-2.6.11-xen-sparse/arch/xen/x86_64/kernel/pci-dma.c
new-xen-64-4/linux-2.6.11-xen-sparse/arch/xen/x86_64/kernel/pci-dma.c
> ---
old-xen-64-4/linux-2.6.11-xen-sparse/arch/xen/x86_64/kernel/pci-dma.c
2005-05-24 17:34:54.000000000 +0000
> +++
new-xen-64-4/linux-2.6.11-xen-sparse/arch/xen/x86_64/kernel/pci-dma.c
2005-06-07 15:35:43.000000000 +0000
> @@ -78,7 +78,7 @@ xen_contig_memory(unsigned long vstart, 
>       pud_t         *pud; 
>       pmd_t         *pmd;
>       pte_t         *pte;
> -     unsigned long  pfn, i, flags;
> +     unsigned long  mfn, i, flags;
>  
>       scrub_pages(vstart, 1 << order);
>  
> @@ -90,16 +90,16 @@ xen_contig_memory(unsigned long vstart, 
>               pud = pud_offset(pgd, (vstart + (i*PAGE_SIZE)));
>               pmd = pmd_offset(pud, (vstart + (i*PAGE_SIZE)));
>               pte = pte_offset_kernel(pmd, (vstart + (i*PAGE_SIZE)));
> -             pfn = pte->pte >> PAGE_SHIFT;
> +             mfn = pte_mfn(*pte);
>               xen_l1_entry_update(pte, 0);
>               phys_to_machine_mapping[(__pa(vstart)>>PAGE_SHIFT)+i] =
>                       (u32)INVALID_P2M_ENTRY;
>               if (HYPERVISOR_dom_mem_op(MEMOP_decrease_reservation, 
> -                                       &pfn, 1, 0) != 1) BUG();
> +                                       &mfn, 1, 0) != 1) BUG();
>       }
>       /* 2. Get a new contiguous memory extent. */
>       if (HYPERVISOR_dom_mem_op(MEMOP_increase_reservation,
> -                               &pfn, 1, order) != 1) BUG();
> +                               &mfn, 1, order) != 1) BUG();
>       /* 3. Map the new extent in place of old pages. */
>       for (i = 0; i < (1<<order); i++) {
>               pgd = pgd_offset_k(   (vstart + (i*PAGE_SIZE)));
> @@ -107,12 +107,12 @@ xen_contig_memory(unsigned long vstart, 
>               pmd = pmd_offset(pud, (vstart + (i*PAGE_SIZE)));
>               pte = pte_offset_kernel(pmd, (vstart + (i*PAGE_SIZE)));
>               xen_l1_entry_update(
> -                     pte, ((pfn+i)<<PAGE_SHIFT)|__PAGE_KERNEL);
> +                     pte, ((mfn+i)<<PAGE_SHIFT)|__PAGE_KERNEL);
>               xen_machphys_update(
> -                     pfn+i, (__pa(vstart)>>PAGE_SHIFT)+i);
> +                     mfn+i, (__pa(vstart)>>PAGE_SHIFT)+i);
>               phys_to_machine_mapping[(__pa(vstart)>>PAGE_SHIFT)+i] =
> -                     pfn+i;
> +                     mfn+i;
>       }
>       /* Flush updates through and flush the TLB. */
>       xen_tlb_flush();
> diff -rN -u -p
old-xen-64-4/linux-2.6.11-xen-sparse/arch/xen/x86_64/mm/hypervisor.c
new-xen-64-4/linux-2.6.11-xen-sparse/arch/xen/x86_64/mm/hypervisor.c
> ---
old-xen-64-4/linux-2.6.11-xen-sparse/arch/xen/x86_64/mm/hypervisor.c
2005-06-06 16:39:54.000000000 +0000
> +++
new-xen-64-4/linux-2.6.11-xen-sparse/arch/xen/x86_64/mm/hypervisor.c
2005-06-07 15:39:31.000000000 +0000
> @@ -256,7 +256,7 @@ unsigned long allocate_empty_lowmem_regi
>          pud = pud_offset(pgd, (vstart + (i*PAGE_SIZE)));
>          pmd = pmd_offset(pud, (vstart + (i*PAGE_SIZE)));
>          pte = pte_offset_kernel(pmd, (vstart + (i*PAGE_SIZE))); 
> -        pfn_array[i] = pte->pte >> PAGE_SHIFT;
> +        pfn_array[i] = pte_mfn(*pte);
>          xen_l1_entry_update(pte, 0);
>          phys_to_machine_mapping[(__pa(vstart)>>PAGE_SHIFT)+i] =
>              (u32)INVALID_P2M_ENTRY;
> diff -rN -u -p
old-xen-64-4/linux-2.6.11-xen-sparse/arch/xen/x86_64/mm/init.c
new-xen-64-4/linux-2.6.11-xen-sparse/arch/xen/x86_64/mm/init.c
> --- old-xen-64-4/linux-2.6.11-xen-sparse/arch/xen/x86_64/mm/init.c
2005-06-02 23:09:31.000000000 +0000
> +++ new-xen-64-4/linux-2.6.11-xen-sparse/arch/xen/x86_64/mm/init.c
2005-06-07 15:39:50.000000000 +0000
> @@ -395,7 +395,7 @@ unsigned long get_machine_pfn(unsigned l
>          pmd_t* pmd = pmd_offset(pud, addr);
>          pte_t *pte = pte_offset_kernel(pmd, addr);
>          
> -        return (pte->pte >> PAGE_SHIFT);
> +        return pte_mfn(*pte);
>  } 
>  
>  #define ALIGN_TO_4K __attribute__((section(".data.page_aligned")))
> diff -rN -u -p
old-xen-64-4/linux-2.6.11-xen-sparse/include/asm-xen/asm-x86_64/pgtable.
h
new-xen-64-4/linux-2.6.11-xen-sparse/include/asm-xen/asm-x86_64/pgtable.
h
> ---
old-xen-64-4/linux-2.6.11-xen-sparse/include/asm-xen/asm-x86_64/pgtable.
h       2005-05-28 09:20:36.000000000 +0000
> +++
new-xen-64-4/linux-2.6.11-xen-sparse/include/asm-xen/asm-x86_64/pgtable.
h       2005-06-07 15:32:47.000000000 +0000
> @@ -277,9 +277,10 @@ static inline unsigned long pud_bad(pud_
>   */
>  #define INVALID_P2M_ENTRY (~0UL)
>  #define FOREIGN_FRAME(_m) ((_m) | (1UL<<((sizeof(unsigned
long)*8)-1)))
> +#define pte_mfn(_pte) ((_pte).pte & PTE_MASK) >> PAGE_SHIFT;
>  #define pte_pfn(_pte)
\
>  ({
\
> -     unsigned long mfn = (_pte).pte >> PAGE_SHIFT;
\
> +     unsigned long mfn = pte_mfn(_pte);
\
>       unsigned pfn = mfn_to_pfn(mfn);
\
>       if ((pfn >= max_mapnr) || (pfn_to_mfn(pfn) != mfn))
\
>               pfn = max_mapnr; /* special: force !pfn_valid() */
\

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> http://lists.xensource.com/xen-devel


-- 
Scott Parish
Signed-off-by: srparish@xxxxxxxxxx

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