From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:37055) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1chGUa-0000Mf-Ow for qemu-devel@nongnu.org; Fri, 24 Feb 2017 09:05:10 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1chGUW-000318-Qv for qemu-devel@nongnu.org; Fri, 24 Feb 2017 09:05:04 -0500 Received: from mx1.redhat.com ([209.132.183.28]:53052) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1chGUW-0002zZ-Ih for qemu-devel@nongnu.org; Fri, 24 Feb 2017 09:05:00 -0500 Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id B9339C05AA5B for ; Fri, 24 Feb 2017 14:05:00 +0000 (UTC) References: <20170206173306.20603-1-dgilbert@redhat.com> <20170206173306.20603-5-dgilbert@redhat.com> From: Laurent Vivier Message-ID: Date: Fri, 24 Feb 2017 15:04:57 +0100 MIME-Version: 1.0 In-Reply-To: <20170206173306.20603-5-dgilbert@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v2 04/16] exec: ram_block_discard_range List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Dr. David Alan Gilbert (git)" , qemu-devel@nongnu.org, quintela@redhat.com Cc: aarcange@redhat.com On 06/02/2017 18:32, Dr. David Alan Gilbert (git) wrote: > From: "Dr. David Alan Gilbert" > > Create ram_block_discard_range in exec.c to replace > postcopy_ram_discard_range and most of ram_discard_range. > > Those two routines are a bit of a weird combination, and > ram_discard_range is about to get more complex for hugepages. > It's OS dependent code (so shouldn't be in migration/ram.c) but > it needs quite a bit of the innards of RAMBlock so doesn't belong in > the os*.c. > > Signed-off-by: Dr. David Alan Gilbert > --- > exec.c | 59 +++++++++++++++++++++++++++++++++++++++++++++++ > include/exec/cpu-common.h | 1 + > 2 files changed, 60 insertions(+) > > diff --git a/exec.c b/exec.c > index 8b9ed73..e040cdf 100644 > --- a/exec.c > +++ b/exec.c > @@ -45,6 +45,12 @@ > #include "exec/address-spaces.h" > #include "sysemu/xen-mapcache.h" > #include "trace-root.h" > + > +#ifdef CONFIG_FALLOCATE_PUNCH_HOLE > +#include > +#include > +#endif > + > #endif > #include "exec/cpu-all.h" > #include "qemu/rcu_queue.h" > @@ -3286,4 +3292,57 @@ int qemu_ram_foreach_block(RAMBlockIterFunc func, void *opaque) > rcu_read_unlock(); > return ret; > } > + > +/* > + * Unmap pages of memory from start to start+length such that > + * they a) read as 0, b) Trigger whatever fault mechanism > + * the OS provides for postcopy. > + * The pages must be unmapped by the end of the function. > + * Returns: 0 on success, none-0 on failure > + * > + */ > +int ram_block_discard_range(RAMBlock *rb, uint64_t start, size_t length) > +{ > + int ret = -1; > + > + rcu_read_lock(); > + uint8_t *host_startaddr = rb->host + start; > + > + if ((uintptr_t)host_startaddr & (rb->page_size - 1)) { > + error_report("ram_block_discard_range: Unaligned start address: %p", > + host_startaddr); > + goto err; > + } > + > + if ((start + length) <= rb->used_length) { > + uint8_t *host_endaddr = host_startaddr + length; > + if ((uintptr_t)host_endaddr & (rb->page_size - 1)) { > + error_report("ram_block_discard_range: Unaligned end address: %p", > + host_endaddr); > + goto err; > + } > + > + errno = ENOTSUP; /* If we are missing MADVISE etc */ > + > +#if defined(CONFIG_MADVISE) > + ret = qemu_madvise(host_startaddr, length, QEMU_MADV_DONTNEED); > +#endif > + if (ret) { > + ret = -errno; > + error_report("ram_block_discard_range: Failed to discard range " > + "%s:%" PRIx64 " +%zx (%d)", > + rb->idstr, start, length, ret); > + } > + } else { > + error_report("ram_block_discard_range: Overrun block '%s' (%" PRIu64 > + "/%zx/" RAM_ADDR_FMT")", > + rb->idstr, start, length, rb->used_length); > + } > + > +err: > + rcu_read_unlock(); > + > + return ret; > +} I really looks like a copy'n'paste from ram_discard_range(). It could be clearer if you remove the code from ram_discard_range() and call this function instead. I think you don't need the "#if defined(CONFIG_MADVISE)" as you use qemu_madvise() (or you should use madvise() directly if you want to avoid the posix_madvise()). [perhaps qemu_madvise() should set errno to ENOTSUP instead of EINVAL] Laurent