From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ian Campbell Subject: Re: [PATCH v3] xen/arm: Fix crash if last memory section is bigger than 1gb Date: Fri, 3 Oct 2014 10:09:56 +0100 Message-ID: <1412327396.423.17.camel@citrix.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Frediano Ziglio Cc: Tim Deegan , Julien Grall , Stefano Stabellini , xen-devel@lists.xen.org List-Id: xen-devel@lists.xenproject.org On Thu, 2014-10-02 at 16:16 +0100, Frediano Ziglio wrote: > setup_xenheap_mappings setup head memory on Arm 32 has a limit of 1gb. > On system with large memory is possible that there are no blocks of memory > smaller than 1gb leading xenheap_pages to be more than 1gb. > This cause memory errors trying to access heap after the 1gb limit. As I mentioned in a previous round of review this explanation doesn't really fit. I think better would be: On arm32 the xenheap has a maximum size of 1GB. On systems with more than 8GB (so 1/8 total RAM is greater than 1GB) there is no point in searching for a region with 1/8 of the total RAM when only 1GB will be used. Therefore limit the maximum size to 1GB before searching. If you agree I will make this change upon commit. > > Signed-off-by: Frediano Ziglio > Reviewed-by: Julien Grall > --- > xen/arch/arm/setup.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/xen/arch/arm/setup.c b/xen/arch/arm/setup.c > index 446de8a..c43c776 100644 > --- a/xen/arch/arm/setup.c > +++ b/xen/arch/arm/setup.c > @@ -500,7 +500,7 @@ static void __init setup_mm(unsigned long > dtb_paddr, size_t dtb_size) > * > * - must be 32 MiB aligned > * - must not include Xen itself or the boot modules > - * - must be at most 1/8 the total RAM in the system > + * - must be at most 1GB or 1/8 the total RAM in the system if less > * - must be at least 128M > * > * We try to allocate the largest xenheap possible within these > @@ -509,6 +509,7 @@ static void __init setup_mm(unsigned long > dtb_paddr, size_t dtb_size) > heap_pages = ram_pages; > xenheap_pages = (heap_pages/8 + 0x1fffUL) & ~0x1fffUL; > xenheap_pages = max(xenheap_pages, 128UL<<(20-PAGE_SHIFT)); > + xenheap_pages = min(xenheap_pages, 1UL<<(30-PAGE_SHIFT)); > > do > {