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[83.57.168.62]) by smtp.gmail.com with ESMTPSA id k15sm4099846wrx.13.2021.10.26.10.00.51 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 26 Oct 2021 10:00:51 -0700 (PDT) Message-ID: Date: Tue, 26 Oct 2021 19:00:51 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.2.0 Subject: Re: [PATCH v2 2/3] memory: Make memory_region_is_mapped() succeed when mapped via an alias To: David Hildenbrand , qemu-devel@nongnu.org References: <20211026160649.47545-1-david@redhat.com> <20211026160649.47545-3-david@redhat.com> From: =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= In-Reply-To: <20211026160649.47545-3-david@redhat.com> Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=philmd@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=170.10.133.124; envelope-from=philmd@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -29 X-Spam_score: -3.0 X-Spam_bar: --- X-Spam_report: (-3.0 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.215, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Eduardo Habkost , Richard Henderson , Peter Xu , Igor Mammedov , Paolo Bonzini Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 10/26/21 18:06, David Hildenbrand wrote: > memory_region_is_mapped() currently does not return "true" when a memory > region is mapped via an alias. > > Assuming we have: > alias (A0) -> alias (A1) -> region (R0) > Mapping A0 would currently only make memory_region_is_mapped() succeed > on A0, but not on A1 and R0. > > Let's fix that by adding a "mapped_via_alias" counter to memory regions and > updating it accordingly when an alias gets (un)mapped. > > I am not aware of actual issues, this is rather a cleanup to make it > consistent. > > Signed-off-by: David Hildenbrand > --- > include/exec/memory.h | 1 + > softmmu/memory.c | 12 +++++++++++- > 2 files changed, 12 insertions(+), 1 deletion(-) > > diff --git a/include/exec/memory.h b/include/exec/memory.h > index a185b6dcb8..35382d9870 100644 > --- a/include/exec/memory.h > +++ b/include/exec/memory.h > @@ -707,6 +707,7 @@ struct MemoryRegion { > const MemoryRegionOps *ops; > void *opaque; > MemoryRegion *container; > + int mapped_via_alias; /* Mapped via an alias, container might be NULL */ > Int128 size; > hwaddr addr; > void (*destructor)(MemoryRegion *mr); > diff --git a/softmmu/memory.c b/softmmu/memory.c > index e5826faa0c..17ca896c38 100644 > --- a/softmmu/memory.c > +++ b/softmmu/memory.c > @@ -2524,8 +2524,13 @@ static void memory_region_add_subregion_common(MemoryRegion *mr, > hwaddr offset, > MemoryRegion *subregion) > { > + MemoryRegion *alias; > + > assert(!subregion->container); > subregion->container = mr; > + for (alias = subregion->alias; alias; alias = alias->alias) { > + alias->mapped_via_alias++; > + } > subregion->addr = offset; > memory_region_update_container_subregions(subregion); > } > @@ -2550,9 +2555,14 @@ void memory_region_add_subregion_overlap(MemoryRegion *mr, > void memory_region_del_subregion(MemoryRegion *mr, > MemoryRegion *subregion) > { > + MemoryRegion *alias; > + > memory_region_transaction_begin(); > assert(subregion->container == mr); > subregion->container = NULL; > + for (alias = subregion->alias; alias; alias = alias->alias) { > + alias->mapped_via_alias--; assert(alias->mapped_via_alias >= 0); > + } > QTAILQ_REMOVE(&mr->subregions, subregion, subregions_link); > memory_region_unref(subregion); > memory_region_update_pending |= mr->enabled && subregion->enabled; > @@ -2649,7 +2659,7 @@ static FlatRange *flatview_lookup(FlatView *view, AddrRange addr) > > bool memory_region_is_mapped(MemoryRegion *mr) > { > - return mr->container ? true : false; > + return !!mr->container || mr->mapped_via_alias; > } > > /* Same as memory_region_find, but it does not add a reference to the > Reviewed-by: Philippe Mathieu-Daudé