From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wei Wang Subject: Re: [PATCH] amd iommu: disable iommu emulation on non-iommu systems Date: Fri, 3 Feb 2012 15:09:23 +0100 Message-ID: <4F2BEA93.6090401@amd.com> References: <4F213167.3010400@amd.com> <4F296F180200007800070594@nat28.tlf.novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4F296F180200007800070594@nat28.tlf.novell.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Jan Beulich Cc: KeirFraser , "xen-devel@lists.xensource.com" , Ian Jackson , Ian Campbell List-Id: xen-devel@lists.xenproject.org On 02/01/2012 04:58 PM, Jan Beulich wrote: >>>> On 26.01.12 at 11:56, Wei Wang wrote: >> --- a/xen/drivers/passthrough/amd/iommu_guest.c Tue Jan 24 16:46:17 2012 +0000 >> +++ b/xen/drivers/passthrough/amd/iommu_guest.c Thu Jan 26 11:50:02 2012 +0100 >> @@ -805,6 +805,9 @@ int guest_iommu_set_base(struct domain * >> p2m_type_t t; >> struct guest_iommu *iommu = domain_iommu(d); >> >> + if ( !is_hvm_domain(d) || !iommu_enabled || !iommuv2_enabled ) >> + return 0; > > Is it really appropriate/correct to return 0 here, while ... good point, will be fixed in the next try. No one use guest_iommu_set_base so far until remaining patches got committed. >> + >> if ( !iommu ) >> return -EACCES; > > ... here it is -EACCES? Further, are the extra checks needed at all > (i.e. wouldn't domain_iommu() return NULL in all of these cases > anyway due to the same checks being added to guest_iommu_init())? > If so, the checks you add to guest_iommu_destroy() are pointless > too. It is just to make sure those functions are not called by an unexpected code path since it is non-static. But I can remove it if you prefer that. Thanks, Wei > Jan > >