From mboxrd@z Thu Jan 1 00:00:00 1970 From: Julien Grall Subject: Re: [PATCH] xen: arm: invalidate caches after map_domain_page done Date: Fri, 01 Aug 2014 10:23:20 +0100 Message-ID: <53DB5C88.8030602@linaro.org> References: <1406877914-31583-1-git-send-email-andrii.tseglytskyi@globallogic.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1406877914-31583-1-git-send-email-andrii.tseglytskyi@globallogic.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Andrii Tseglytskyi , xen-devel@lists.xen.org, Ian Campbell , Stefano Stabellini , Tim Deegan List-Id: xen-devel@lists.xenproject.org Hi Andrii, On 01/08/14 08:25, Andrii Tseglytskyi wrote: > In some cases, memory page returned by map_domain_page() contains > invalid data. Issue is observed when map_domain_page() is used > immediately after p2m_lookup() function, when random page of > guest domain memory is need to be mapped to xen. Data on this > already memory page may be not valid. Issue is fixed when > caches are invalidated after mapping is done. > > Signed-off-by: Andrii Tseglytskyi > --- > xen/arch/arm/mm.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c > index 0a243b0..085780a 100644 > --- a/xen/arch/arm/mm.c > +++ b/xen/arch/arm/mm.c > @@ -304,7 +304,7 @@ void *map_domain_page(unsigned long mfn) > * We may not have flushed this specific subpage at map time, > * since we only flush the 4k page not the superpage > */ > - flush_xen_data_tlb_range_va_local(va, PAGE_SIZE); Why did you remove the flush TLB? It's requirement to make sure the VA will pointed to the right PA. > + clean_and_invalidate_xen_dcache_va_range((void *)va, PAGE_SIZE); This is not the right approach, map_domain_page is heavily used to map hypercall data page. Those pages must reside in normal inner-cacheable memory. So cleaning the cache is useless and time consuming. If you want to clean and invalidate the cache, even though I don't think this right by reading the commit message, you have to introduce a new helper. > return (void *)va; > } > Regards, -- Julien Grall