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[95.62.39.214]) by smtp.gmail.com with ESMTPSA id u19-20020a05600c211300b003f17a00c214sm3054433wml.16.2023.04.19.12.42.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 19 Apr 2023 12:42:59 -0700 (PDT) From: Juan Quintela To: Peter Xu Cc: qemu-devel@nongnu.org, Paolo Bonzini , Daniel P . =?utf-8?Q?Berrang=C3=A9?= , Leonardo Bras Soares Passos , David Hildenbrand Subject: Re: [PATCH v2 3/4] migration/postcopy: Detect file system on dest host In-Reply-To: <20230419161739.1129988-4-peterx@redhat.com> (Peter Xu's message of "Wed, 19 Apr 2023 12:17:38 -0400") References: <20230419161739.1129988-1-peterx@redhat.com> <20230419161739.1129988-4-peterx@redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.2 (gnu/linux) Date: Wed, 19 Apr 2023 21:42:58 +0200 Message-ID: <87354v1wvx.fsf@secure.mitica> MIME-Version: 1.0 Content-Type: text/plain Received-SPF: pass client-ip=170.10.129.124; envelope-from=quintela@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 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, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: quintela@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Peter Xu wrote: > Postcopy requires the memory support userfaultfd to work. Right now we > check it but it's a bit too late (when switching to postcopy migration). > > Do that early right at enabling of postcopy. > > Note that this is still only a best effort because ramblocks can be > dynamically created. We can add check in hostmem creations and fail if > postcopy enabled, but maybe that's too aggressive. > > Still, we have chance to fail the most obvious where we know there's an > existing unsupported ramblock. > > Signed-off-by: Peter Xu Reviewed-by: Juan Quintela > -static int test_ramblock_postcopiable(RAMBlock *rb, void *opaque) > +static int test_ramblock_postcopiable(RAMBlock *rb) This should return a bool, right? Notice that it was already there, just noticing. > { > const char *block_name = qemu_ram_get_idstr(rb); > ram_addr_t length = qemu_ram_get_used_length(rb); > size_t pagesize = qemu_ram_pagesize(rb); > + QemuFsType fs; You can move the variable definition to the only block that it is used. > if (length % pagesize) { > error_report("Postcopy requires RAM blocks to be a page size multiple," > @@ -348,6 +350,15 @@ static int test_ramblock_postcopiable(RAMBlock *rb, void *opaque) > "page size of 0x%zx", block_name, length, pagesize); > return 1; > } > + > + if (rb->fd >= 0) { > + fs = qemu_fd_getfs(rb->fd); Minor nit: Seeing it in use, I wonder if it is clearer to name the function: qemu_fd_get_filesystem(fd) > + if (fs != QEMU_FS_TYPE_TMPFS && fs != QEMU_FS_TYPE_HUGETLBFS) { > + error_report("Host backend files need to be TMPFS or HUGETLBFS only"); I think that the "only" is not needed on that error message. > + return 1; > + } > + } > + > return 0; > } > > @@ -366,6 +377,7 @@ bool postcopy_ram_supported_by_host(MigrationIncomingState *mis) > struct uffdio_range range_struct; > uint64_t feature_mask; > Error *local_err = NULL; > + RAMBlock *block; > > if (qemu_target_page_size() > pagesize) { > error_report("Target page size bigger than host page size"); > @@ -390,9 +402,23 @@ bool postcopy_ram_supported_by_host(MigrationIncomingState *mis) > goto out; > } > > - /* We don't support postcopy with shared RAM yet */ > - if (foreach_not_ignored_block(test_ramblock_postcopiable, NULL)) { > - goto out; > + /* > + * We don't support postcopy with some type of ramblocks. > + * > + * NOTE: we explicitly ignored ramblock_is_ignored() instead we checked > + * all possible ramblocks. This is because this function can be called > + * when creating the migration object, during the phase RAM_MIGRATABLE > + * is not even properly set for all the ramblocks. > + * > + * A side effect of this is we'll also check against RAM_SHARED > + * ramblocks even if migrate_ignore_shared() is set (in which case > + * we'll never migrate RAM_SHARED at all), but normally this shouldn't > + * affect in reality, or we can revisit. > + */ I think we can tweak the English of that two paragraphs. > + RAMBLOCK_FOREACH(block) { > + if (test_ramblock_postcopiable(block)) { > + goto out; > + } > } > > /* In the big scheme of things, patch is ok for me. Later, Juan.