Messages in this thread | | | Subject | Re: [PATCH] xen/p2m: fix extra memory regions accounting | From | Juergen Gross <> | Date | Thu, 3 Sep 2015 14:25:42 +0200 |
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On 09/03/2015 02:05 PM, Roger Pau Monne wrote: > On systems with memory maps with ranges that don't end at page boundaries, > like: > > [...] > (XEN) 0000000000100000 - 00000000dfdf9c00 (usable) > (XEN) 00000000dfdf9c00 - 00000000dfe4bc00 (ACPI NVS) > [...] > > xen_add_extra_mem will create a protected range that ends up at 0xdfdf9c00, > but the function used to check if a memory address is inside of a protected > range works with pfns, which means that an attempt to map 0xdfdf9c00 will be > refused because the check is performed against 0xdfdf9000 instead of > 0xdfdf9c00. > > In order to fix this, make sure that the ranges that are added to the > xen_extra_mem array are aligned to page boundaries. > > Signed-off-by: Roger Pau Monné <roger.pau@citrix.com> > Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> > Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> > Cc: David Vrabel <david.vrabel@citrix.com> > Cc: Juergen Gross <jgross@suse.com> > Cc: xen-devel@lists.xenproject.org > --- > AFAICT this patch needs to be backported to 3.19, 4.0, 4.1 and 4.2. > --- > arch/x86/xen/setup.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c > index 55f388e..dcf5865 100644 > --- a/arch/x86/xen/setup.c > +++ b/arch/x86/xen/setup.c > @@ -68,6 +68,9 @@ static void __init xen_add_extra_mem(phys_addr_t start, phys_addr_t size) > { > int i; > > + start = PAGE_ALIGN(start); > + size &= PAGE_MASK;
This is not correct. If start wasn't page aligned and size was, you'll add one additional page to xen_extra_mem.
> + > for (i = 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++) { > /* Add new region. */ > if (xen_extra_mem[i].size == 0) { > @@ -92,6 +95,9 @@ static void __init xen_del_extra_mem(phys_addr_t start, phys_addr_t size) > int i; > phys_addr_t start_r, size_r; > > + start = PAGE_ALIGN(start); > + size &= PAGE_MASK;
Not really needed, as xen_del_extra_mem() is called with aligned values only. OTOH it does no harm, as long as you correct size as above.
> + > for (i = 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++) { > start_r = xen_extra_mem[i].start; > size_r = xen_extra_mem[i].size; >
Juergen
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