[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [PATCH v3 05/19] xen/arm: mm: Add support for the contiguous bit
Hi, On 02/04/2022 00:53, Stefano Stabellini wrote: On Mon, 21 Feb 2022, Julien Grall wrote:@@ -1333,21 +1386,34 @@ static int xen_pt_update(unsigned long virt, while ( left ) { unsigned int order, level; + unsigned int nr_contig; + unsigned int new_flags;level = xen_pt_mapping_level(vfn, mfn, left, flags);order = XEN_PT_LEVEL_ORDER(level);ASSERT(left >= BIT(order, UL)); - rc = xen_pt_update_entry(root, pfn_to_paddr(vfn), mfn, level, flags);- if ( rc ) - break; + /* + * Check if we can set the contiguous mapping and update the + * flags accordingly. + */ + nr_contig = xen_pt_check_contig(vfn, mfn, level, left, flags); + new_flags = flags | ((nr_contig > 1) ? _PAGE_CONTIG : 0);Here is an optional idea to make the code simpler. We could move the flags changes (adding/removing _PAGE_CONTIG) to xen_pt_check_contig. That way, we could remove the inner loop. xen_pt_check_contig could check if _PAGE_CONTIG is already set and based on alignment, it should be able to figure out when it needs to be disabled. My initial attempt was to do everything in a loop. But this didn't pan out as I wanted (I felt the code was complex) and there are extra work to be done for the next 31 entries (assuming 4KB granularity). Hence the two loops. Unfortunately, I didn't keep my first attempt. So I can't realy show what I wrote. Cheers, -- Julien Grall
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