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bh=gq6A4Pmc9D+wI4Z4Xz25DoQrl3qHiAAck89mQP9dahw=; b=FmOIftKy1BbaE+eAQzUjbpupW6wQoobfgpaug3rs71eCcXGPuAbuOC7savNwPQD+YNtrFo 5E8vuqZScw8YzU5YB5BUaEfSHbai0zmD/GmwI95HCdtTLdGRtYvVIxzJgQXAzAvdj9YVrt v0gLSXyhLb5+XpLaNZQZxSo0aQXb2ZY= X-MC-Unique: Aj7CYDDlNLuGvGuePXWmVg-1 From: Paolo Bonzini To: qemu-devel@nongnu.org Subject: [PULL 09/31] exec: fetch the alignment of Linux devdax pmem character device nodes Date: Wed, 24 Jun 2020 06:50:26 -0400 Message-Id: <20200624105048.375353-9-pbonzini@redhat.com> In-Reply-To: <20200624104917.375143-1-pbonzini@redhat.com> References: <20200624104917.375143-1-pbonzini@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=pbonzini@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; 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charset="utf-8" From: Jingqi Liu If the backend file is devdax pmem character device, the alignment specified by the option 'align=3DNUM' in the '-object memory-backend-file' needs to match the alignment requirement of the devdax pmem character devic= e. This patch uses the interfaces of libdaxctl to fetch the devdax pmem file 'align', so that we can compare it with the NUM of 'align=3DNUM'. The NUM needs to be larger than or equal to the devdax pmem file 'align'. It also fixes the problem that mmap() returns failure in qemu_ram_mmap() when the NUM of 'align=3DNUM' is less than the devdax pmem file 'align'. Suggested-by: Dan Williams Reviewed-by: Joao Martins Signed-off-by: Jingqi Liu Message-Id: <20200429085011.63752-2-jingqi.liu@intel.com> Signed-off-by: Paolo Bonzini --- exec.c | 54 +++++++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 53 insertions(+), 1 deletion(-) diff --git a/exec.c b/exec.c index d6712fba7e..37c921f364 100644 --- a/exec.c +++ b/exec.c @@ -77,6 +77,10 @@ =20 #include "monitor/monitor.h" =20 +#ifdef CONFIG_LIBDAXCTL +#include +#endif + //#define DEBUG_SUBPAGE =20 #if !defined(CONFIG_USER_ONLY) @@ -1745,6 +1749,46 @@ static int64_t get_file_size(int fd) return size; } =20 +static int64_t get_file_align(int fd) +{ + int64_t align =3D -1; +#if defined(__linux__) && defined(CONFIG_LIBDAXCTL) + struct stat st; + + if (fstat(fd, &st) < 0) { + return -errno; + } + + /* Special handling for devdax character devices */ + if (S_ISCHR(st.st_mode)) { + g_autofree char *path =3D NULL; + g_autofree char *rpath =3D NULL; + struct daxctl_ctx *ctx; + struct daxctl_region *region; + int rc =3D 0; + + path =3D g_strdup_printf("/sys/dev/char/%d:%d", + major(st.st_rdev), minor(st.st_rdev)); + rpath =3D realpath(path, NULL); + + rc =3D daxctl_new(&ctx); + if (rc) { + return -1; + } + + daxctl_region_foreach(ctx, region) { + if (strstr(rpath, daxctl_region_get_path(region))) { + align =3D daxctl_region_get_align(region); + break; + } + } + daxctl_unref(ctx); + } +#endif /* defined(__linux__) && defined(CONFIG_LIBDAXCTL) */ + + return align; +} + static int file_ram_open(const char *path, const char *region_name, bool *created, @@ -2296,7 +2340,7 @@ RAMBlock *qemu_ram_alloc_from_fd(ram_addr_t size, Mem= oryRegion *mr, { RAMBlock *new_block; Error *local_err =3D NULL; - int64_t file_size; + int64_t file_size, file_align; =20 /* Just support these ram flags by now. */ assert((ram_flags & ~(RAM_SHARED | RAM_PMEM)) =3D=3D 0); @@ -2332,6 +2376,14 @@ RAMBlock *qemu_ram_alloc_from_fd(ram_addr_t size, Me= moryRegion *mr, return NULL; } =20 + file_align =3D get_file_align(fd); + if (file_align > 0 && mr && file_align > mr->align) { + error_setg(errp, "backing store align 0x%" PRIx64 + " is larger than 'align' option 0x" RAM_ADDR_FMT, + file_align, mr->align); + return NULL; + } + new_block =3D g_malloc0(sizeof(*new_block)); new_block->mr =3D mr; new_block->used_length =3D size; --=20 2.26.2