| Message ID | 1475176178-4873-3-git-send-email-dgilbert@redhat.com |
|---|---|
| State | New |
| Headers | show |
On Thu, Sep 29, 2016 at 08:09:38PM +0100, Dr. David Alan Gilbert (git) wrote: > From: "Dr. David Alan Gilbert" <dgilbert@redhat.com> > > At the moment postcopy will fail as soon as qemu tries to register > userfault on the RAMBlock pages that are backed by hugepages. > However, the kernel is going to get userfault support for hugepage > at some point, and we've not got the rest of the QEMU code to support > it yet, so fail neatly with an error like: > > Postcopy doesn't support hugetlbfs yet (/objects/mem1) > > Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com> > --- > migration/postcopy-ram.c | 23 +++++++++++++++++++++++ > 1 file changed, 23 insertions(+) > > diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c > index 9b04778..9723593 100644 > --- a/migration/postcopy-ram.c > +++ b/migration/postcopy-ram.c > @@ -85,6 +85,23 @@ static bool ufd_version_check(int ufd) > } > > /* > + * Check for things that postcopy won't support; returns 0 if the block > + * is fine. > + */ > +static int check_range(const char *block_name, void *host_addr, > + ram_addr_t offset, ram_addr_t length, void *opaque) > +{ > + RAMBlock *rb = qemu_ram_block_by_name(block_name); > + > + if (qemu_ram_pagesize(rb) > getpagesize()) { > + error_report("Postcopy doesn't support hugetlbfs yet (%s)", block_name); A small nitpick - I'd suggest s/hugetlbfs/large page sizes/ as this error will ultimately bubble up to users, and 'large page sizes' is the conceptual feature Regards, Daniel
* Daniel P. Berrange (berrange@redhat.com) wrote: > On Thu, Sep 29, 2016 at 08:09:38PM +0100, Dr. David Alan Gilbert (git) wrote: > > From: "Dr. David Alan Gilbert" <dgilbert@redhat.com> > > > > At the moment postcopy will fail as soon as qemu tries to register > > userfault on the RAMBlock pages that are backed by hugepages. > > However, the kernel is going to get userfault support for hugepage > > at some point, and we've not got the rest of the QEMU code to support > > it yet, so fail neatly with an error like: > > > > Postcopy doesn't support hugetlbfs yet (/objects/mem1) > > > > Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com> > > --- > > migration/postcopy-ram.c | 23 +++++++++++++++++++++++ > > 1 file changed, 23 insertions(+) > > > > diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c > > index 9b04778..9723593 100644 > > --- a/migration/postcopy-ram.c > > +++ b/migration/postcopy-ram.c > > @@ -85,6 +85,23 @@ static bool ufd_version_check(int ufd) > > } > > > > /* > > + * Check for things that postcopy won't support; returns 0 if the block > > + * is fine. > > + */ > > +static int check_range(const char *block_name, void *host_addr, > > + ram_addr_t offset, ram_addr_t length, void *opaque) > > +{ > > + RAMBlock *rb = qemu_ram_block_by_name(block_name); > > + > > + if (qemu_ram_pagesize(rb) > getpagesize()) { > > + error_report("Postcopy doesn't support hugetlbfs yet (%s)", block_name); > > A small nitpick - I'd suggest s/hugetlbfs/large page sizes/ as this error > will ultimately bubble up to users, and 'large page sizes' is the conceptual > feature Interesting, I'd never heard it called 'large' before. Everytime I just say 'huge page' to someone I then have to explain it's fine on transparent huge page. Dave > > > Regards, > Daniel > -- > |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| > |: http://libvirt.org -o- http://virt-manager.org :| > |: http://entangle-photo.org -o- http://search.cpan.org/~danberr/ :| -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
"Daniel P. Berrange" <berrange@redhat.com> wrote: > On Thu, Sep 29, 2016 at 08:09:38PM +0100, Dr. David Alan Gilbert (git) wrote: >> From: "Dr. David Alan Gilbert" <dgilbert@redhat.com> >> >> At the moment postcopy will fail as soon as qemu tries to register >> userfault on the RAMBlock pages that are backed by hugepages. >> However, the kernel is going to get userfault support for hugepage >> at some point, and we've not got the rest of the QEMU code to support >> it yet, so fail neatly with an error like: >> >> Postcopy doesn't support hugetlbfs yet (/objects/mem1) >> >> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com> >> --- >> migration/postcopy-ram.c | 23 +++++++++++++++++++++++ >> 1 file changed, 23 insertions(+) >> >> diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c >> index 9b04778..9723593 100644 >> --- a/migration/postcopy-ram.c >> +++ b/migration/postcopy-ram.c >> @@ -85,6 +85,23 @@ static bool ufd_version_check(int ufd) >> } >> >> /* >> + * Check for things that postcopy won't support; returns 0 if the block >> + * is fine. >> + */ >> +static int check_range(const char *block_name, void *host_addr, >> + ram_addr_t offset, ram_addr_t length, void *opaque) >> +{ >> + RAMBlock *rb = qemu_ram_block_by_name(block_name); >> + >> + if (qemu_ram_pagesize(rb) > getpagesize()) { >> + error_report("Postcopy doesn't support hugetlbfs yet (%s)", block_name); > > A small nitpick - I'd suggest s/hugetlbfs/large page sizes/ as this error > will ultimately bubble up to users, and 'large page sizes' is the conceptual > feature Reviewed-by: Juan Quintela <quintela@redhat.com> I fixed the message my hand
diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c index 9b04778..9723593 100644 --- a/migration/postcopy-ram.c +++ b/migration/postcopy-ram.c @@ -85,6 +85,23 @@ static bool ufd_version_check(int ufd) } /* + * Check for things that postcopy won't support; returns 0 if the block + * is fine. + */ +static int check_range(const char *block_name, void *host_addr, + ram_addr_t offset, ram_addr_t length, void *opaque) +{ + RAMBlock *rb = qemu_ram_block_by_name(block_name); + + if (qemu_ram_pagesize(rb) > getpagesize()) { + error_report("Postcopy doesn't support hugetlbfs yet (%s)", block_name); + return -E2BIG; + } + + return 0; +} + +/* * Note: This has the side effect of munlock'ing all of RAM, that's * normally fine since if the postcopy succeeds it gets turned back on at the * end. @@ -104,6 +121,12 @@ bool postcopy_ram_supported_by_host(void) goto out; } + /* Check for anything about the RAMBlocks we don't support */ + if (qemu_ram_foreach_block(check_range, NULL)) { + /* check_range will have printed its own error */ + goto out; + } + ufd = syscall(__NR_userfaultfd, O_CLOEXEC); if (ufd == -1) { error_report("%s: userfaultfd not available: %s", __func__,