From mboxrd@z Thu Jan 1 00:00:00 1970 From: Julien Grall Subject: Re: [PATCH v2 1/2] xen: introduce arch_iommu_grant_(un)map_page Date: Thu, 24 Jul 2014 12:18:28 +0100 Message-ID: <53D0EB84.9020303@linaro.org> References: <1406135982-15487-1-git-send-email-stefano.stabellini@eu.citrix.com> <53D0E531.80303@linaro.org> <53D0EAA7.6090008@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" 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: Stefano Stabellini Cc: julien.grall@citrix.com, xen-devel@lists.xensource.com, Ian.Campbell@citrix.com List-Id: xen-devel@lists.xenproject.org On 24/07/14 12:16, Stefano Stabellini wrote: > On Thu, 24 Jul 2014, Julien Grall wrote: >> On 24/07/14 12:07, Stefano Stabellini wrote: >>> On Thu, 24 Jul 2014, Julien Grall wrote: >>>> Hi Stefano, >>>> >>>> The Title of the commit message is now wrong. >>> >>> Thanks, I didn't notice. >>> >>> >>>> On 23/07/14 18:19, Stefano Stabellini wrote: >>>>> Introduce two arch specific functions to create a new p2m mapping of >>>>> granted pages at pfn == mfn. >>>>> The x86 implementation just returns ENOSYS. >>>>> >>>>> Signed-off-by: Stefano Stabellini >>>>> --- >>>>> xen/arch/arm/p2m.c | 19 +++++++++++++++++++ >>>>> xen/include/asm-arm/p2m.h | 4 ++++ >>>>> xen/include/asm-x86/p2m.h | 13 +++++++++++++ >>>>> 3 files changed, 36 insertions(+) >>>>> >>>>> diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c >>>>> index 9960e17..c38af59 100644 >>>>> --- a/xen/arch/arm/p2m.c >>>>> +++ b/xen/arch/arm/p2m.c >>>>> @@ -555,6 +555,25 @@ void guest_physmap_remove_page(struct domain *d, >>>>> pfn_to_paddr(mfn), MATTR_MEM, p2m_invalid); >>>>> } >>>>> >>>>> +int arch_grant_map_page_identity(struct domain *d, unsigned long frame, >>>>> + bool_t writeable) >>>>> +{ >>>>> + p2m_type_t t; >>>>> + >>>>> + if ( writeable ) >>>>> + t = p2m_ram_rw; >>>>> + else >>>>> + t = p2m_ram_ro; >>>> >>>> This is not the right p2m type to use here. p2m_ram_{rw,ro} allow foreign >>>> mapping. So another guest could access to the grant. >>>> >>>> I would use p2m_iommu_map_{rw,ro}. >>> >>> >>> I see. I'll make the change and add a comment to explain why we are >>> using p2m_iommu types for non-iommu related mappings. >> >> The code to add the 1:1 mapping for the SMMU is very ugly. I was wondering if >> we could drop the iommu_map_page callback and >> directly use arch_grant_map_page_identity in all the case. >> >> It would avoid the if/else in the grant code. > > Thing is arch_grant_map_page_identity has nothing to do with IOMMUs. It > gets confusing, especially on x86 where people don't know why we need > this. The if/else is ugly but clearer. > See also the previous email exchange with Jan. Ok. So could we call this function from iommu_map_page on the SMMU? It would at least avoid duplicating the code? Regards, -- Julien Grall