| Message ID | 20190320154338.24124-1-wei.liu2@citrix.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] libxc: fix HVM core dump | expand |
Wei Liu writes ("[PATCH v2] libxc: fix HVM core dump"):
> f969bc9fc96 forbid get_address_size call on HVM guests, because that
> didn't make sense. It broke core dump functionality on HVM because
> libxc unconditionally asked for guest width.
>
> Force guest_width to a sensible value.
>
> Reported-by: Igor Druzhinin <igor.druzhinin@citrix.com>
> Signed-off-by: Wei Liu <wei.liu2@citrix.com>
LGTM. Thanks for the copious comment.
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
On Wed, Mar 20, 2019 at 04:40:59PM +0000, Ian Jackson wrote: > Wei Liu writes ("[PATCH v2] libxc: fix HVM core dump"): > > f969bc9fc96 forbid get_address_size call on HVM guests, because that > > didn't make sense. It broke core dump functionality on HVM because > > libxc unconditionally asked for guest width. > > > > Force guest_width to a sensible value. > > > > Reported-by: Igor Druzhinin <igor.druzhinin@citrix.com> > > Signed-off-by: Wei Liu <wei.liu2@citrix.com> > > LGTM. Thanks for the copious comment. > > Acked-by: Ian Jackson <ian.jackson@eu.citrix.com> Thanks. Pushed. Wei.
On 20/03/2019 16:43, Wei Liu wrote: > f969bc9fc96 forbid get_address_size call on HVM guests, because that > didn't make sense. It broke core dump functionality on HVM because > libxc unconditionally asked for guest width. > > Force guest_width to a sensible value. > > Reported-by: Igor Druzhinin <igor.druzhinin@citrix.com> > Signed-off-by: Wei Liu <wei.liu2@citrix.com> > --- > Cc: Ian Jackson <ian.jackson@eu.citrix.com> > Cc: Jan Beulich <jbeulich@suse.com> > Cc: Andrew Cooper <andrew.cooper3@citrix.com> > Cc: Igor Druzhinin <igor.druzhinin@citrix.com> > Cc: Juergen Gross <jgross@suse.com> > > Juergen, this is probably too late for 4.12, but you can at least add > a release note somewhere. > > Ian, please backport this to 4.12. As we have another blocker I'm fine with this patch for 4.12: Release-acked-by: Juergen Gross <jgross@suse.com> Juergen
diff --git a/tools/libxc/xc_core.c b/tools/libxc/xc_core.c index e581905ba9..2ee1d205b4 100644 --- a/tools/libxc/xc_core.c +++ b/tools/libxc/xc_core.c @@ -459,12 +459,6 @@ xc_domain_dumpcore_via_callback(xc_interface *xch, struct xc_core_section_headers *sheaders = NULL; Elf64_Shdr *shdr; - if ( xc_domain_get_guest_width(xch, domid, &dinfo->guest_width) != 0 ) - { - PERROR("Could not get address size for domain"); - return sts; - } - xc_core_arch_context_init(&arch_ctxt); if ( (dump_mem_start = malloc(DUMP_INCREMENT*PAGE_SIZE)) == NULL ) { @@ -487,6 +481,40 @@ xc_domain_dumpcore_via_callback(xc_interface *xch, } auto_translated_physmap = xc_core_arch_auto_translated_physmap(&info); + if ( !auto_translated_physmap ) + + { + if ( xc_domain_get_guest_width(xch, domid, &dinfo->guest_width) != 0 ) + { + PERROR("Could not get address size for domain"); + goto out; + } + } + else + { + /* + * Autotranslated guest never sets guest width in the first + * place. Force guest_width to be sizeof(unsigned long) so + * code below functions properly. + * + * Here is why this is correct. + * + * 1. Before f969bc9fc, xc_domain_get_guest_width for HVM (x86 + * and ARM) always returned hypervisor's idea of + * sizeof(unsigned long). + * + * 2. There has never been a situation in which hypervisor's + * word width is smaller than toolstack domain's (i.e. no + * 32bit hypervisor + 64bit toolstack). + * + * Predicates in code test guest_width against toolstack + * domain's sizeof(unsigned long), so setting guest_width to + * toolstack domain's idea of sizeof(unsigned long) matches + * the original behaviour for HVM guests. + */ + dinfo->guest_width = sizeof(unsigned long); + } + if ( domid != info.domid ) { PERROR("Domain %d does not exist", domid);
f969bc9fc96 forbid get_address_size call on HVM guests, because that didn't make sense. It broke core dump functionality on HVM because libxc unconditionally asked for guest width. Force guest_width to a sensible value. Reported-by: Igor Druzhinin <igor.druzhinin@citrix.com> Signed-off-by: Wei Liu <wei.liu2@citrix.com> --- Cc: Ian Jackson <ian.jackson@eu.citrix.com> Cc: Jan Beulich <jbeulich@suse.com> Cc: Andrew Cooper <andrew.cooper3@citrix.com> Cc: Igor Druzhinin <igor.druzhinin@citrix.com> Cc: Juergen Gross <jgross@suse.com> Juergen, this is probably too late for 4.12, but you can at least add a release note somewhere. Ian, please backport this to 4.12. --- tools/libxc/xc_core.c | 40 ++++++++++++++++++++++++++++++++++------ 1 file changed, 34 insertions(+), 6 deletions(-)