From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Chen, Tiejun" Subject: Re: [v7][RFC][PATCH 08/13] xen/x86/p2m: set p2m_access_n for reserved device memory mapping Date: Tue, 04 Nov 2014 09:35:21 +0800 Message-ID: <54582D59.4020201@intel.com> References: <1414136077-18599-1-git-send-email-tiejun.chen@intel.com> <1414136077-18599-9-git-send-email-tiejun.chen@intel.com> <544A88560200007800042056@mail.emea.novell.com> <544E0ACA.8050201@intel.com> <544E2D8002000078000425A9@mail.emea.novell.com> <544F531C.7060401@intel.com> <544F7A310200007800042BAC@mail.emea.novell.com> <5450A330.6020102@intel.com> <5450BF63020000780004305E@mail.emea.novell.com> <5451EB48.9010103@intel.com> <545211DA0200007800043645@mail.emea.novell.com> <5452F8D8.9050009@intel.com> <545355720200007800043D97@mail.emea.novell.com> <54571E91.4030903@intel.com> <5457523A02000078000443C7@mail.emea.novell.com> <54575013.50702@intel.com> <545760FD0200007800044474@mail.emea.novell.com> <54576B9B.1060601@intel.com> <54577AD302000078000445EB@mail.emea.novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <54577AD302000078000445EB@mail.emea.novell.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: Jan Beulich Cc: yang.z.zhang@intel.com, kevin.tian@intel.com, tim@xen.org, xen-devel@lists.xen.org List-Id: xen-devel@lists.xenproject.org On 2014/11/3 19:53, Jan Beulich wrote: >>>> On 03.11.14 at 12:48, wrote: >> On 2014/11/3 18:03, Jan Beulich wrote: >>>>>> On 03.11.14 at 10:51, wrote: >>>> On 2014/11/3 17:00, Jan Beulich wrote: >>>>>>>> On 03.11.14 at 07:20, wrote: >>>>>> #2 the error handling >>>>>> >>>>>> In an error case what should I do? Currently we still create these >>>>>> mapping as normal. This means these mfns will be valid so later we can't >>>>>> set them again then device can't be assigned as passthrough. I think >>>>>> this makes sense. Or we should just stop them from setting 1:1 mapping? >>>>> >>>>> You should, with very few exceptions, not ignore errors (which >>>>> includes "handling" them by just logging a message. Instead, you >>>>> should propagate the error back up the call chain. >>>>> >>>> >>>> Do you mean in your patch, >>>> >>>> +int iommu_get_reserved_device_memory(iommu_grdm_t *func, void *ctxt) >>>> +{ >>>> + const struct iommu_ops *ops = iommu_get_ops(); >>>> + >>>> + if ( !iommu_enabled || !ops->get_reserved_device_memory ) >>>> + return 0; >>>> + >>>> + return ops->get_reserved_device_memory(func, ctxt); >>>> +} >>>> + >>>> >>>> I shouldn't return that directly. Then instead, we should handle all >>>> error scenarios here? >>> >>> No. All error scenarios are already being handled here (by >>> propagating the error code to the caller). >> >> Sorry, how to propagate the error code? > > Return it to the caller (and it will do so onwards, until it reaches > [presumably] the entity having invoked a hypercall). I guess you mean we should return out in this error case, @@ -686,8 +686,25 @@ guest_physmap_add_entry(struct domain *d, unsigned long gfn, /* Now, actually do the two-way mapping */ if ( mfn_valid(_mfn(mfn)) ) { - rc = p2m_set_entry(p2m, gfn, _mfn(mfn), page_order, t, - p2m->default_access); + rc = 0; + a = p2m->default_access; + if ( !is_hardware_domain(d) ) + { + rc = iommu_get_reserved_device_memory(p2m_check_reserved_device_memory, + &gfn); + /* We always avoid populating reserved device memory. */ + if ( rc == 1 ) + goto out; + else if ( rc < 0 ) + { + printk(XENLOG_G_WARNING + "Dom%d can't check reserved device memory.\n", + d->domain_id); + goto out; + } + } + + rc = p2m_set_entry(p2m, gfn, _mfn(mfn), page_order, t, a); if ( rc ) goto out; /* Failed to update p2m, bail without updating m2p. */ Thanks Tiejun