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[79.242.61.118]) by smtp.gmail.com with ESMTPSA id l124sm3470911wml.8.2021.10.27.05.12.26 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 27 Oct 2021 05:12:26 -0700 (PDT) Message-ID: <6ed7c905-1652-75ac-4dbe-e16bbd1bb40e@redhat.com> Date: Wed, 27 Oct 2021 14:12:26 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.1.0 Subject: Re: [PATCH v2 2/3] memory: Make memory_region_is_mapped() succeed when mapped via an alias To: =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= , qemu-devel@nongnu.org References: <20211026160649.47545-1-david@redhat.com> <20211026160649.47545-3-david@redhat.com> From: David Hildenbrand Organization: Red Hat In-Reply-To: Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=david@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=david@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -55 X-Spam_score: -5.6 X-Spam_bar: ----- X-Spam_report: (-5.6 / 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=-2.847, 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 26.10.21 19:00, Philippe Mathieu-Daudé wrote: > 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); Makes sense, I'll respin with that -- thanks! -- Thanks, David / dhildenb