Re: [PATCH 1/2] libxl: Fix guest kexec - skip cpuid policy

[Juergen Gross <jgross@xxxxxxxx>]

On 21.01.23 22:39, Jason Andryuk wrote:
> When a domain performs a kexec (soft reset), libxl__build_pre() is
> called with the existing domid.  Calling libxl__cpuid_legacy() on the
> existing domain fails since the cpuid policy has already been set, and
> the guest isn't rebuilt and doesn't kexec.
>
> xc: error: Failed to set d1's policy (err leaf 0xffffffff, subleaf 0xffffffff, 
> msr 0xffffffff) (17 = File exists): Internal error
> libxl: error: libxl_cpuid.c:494:libxl__cpuid_legacy: Domain 1:Failed to apply 
> CPUID policy: File exists
> libxl: error: libxl_create.c:1641:domcreate_rebuild_done: Domain 1:cannot 
> (re-)build domain: -3
> libxl: error: libxl_xshelp.c:201:libxl__xs_read_mandatory: xenstore read 
> failed: `/libxl/1/type': No such file or directory
> libxl: warning: libxl_dom.c:49:libxl__domain_type: unable to get domain type 
> for domid=1, assuming HVM
>
> During a soft_reset, skip calling libxl__cpuid_legacy() to avoid the
> issue.  Before the fixes commit, the libxl__cpuid_legacy() failure would
> have been ignored, so kexec would continue.
>
> Fixes: 34990446ca91 "libxl: don't ignore the return value from 
> xc_cpuid_apply_policy"
> Signed-off-by: Jason Andryuk <jandryuk@xxxxxxxxx>
> ---
> Probably a backport candidate since this has been broken for a while.
> ---
>   tools/libs/light/libxl_create.c   | 4 ++--
>   tools/libs/light/libxl_dom.c      | 5 +++--
>   tools/libs/light/libxl_internal.h | 2 +-
>   3 files changed, 6 insertions(+), 5 deletions(-)
>
> diff --git a/tools/libs/light/libxl_create.c b/tools/libs/light/libxl_create.c
> index 5cddc3df79..587a515dff 100644
> --- a/tools/libs/light/libxl_create.c
> +++ b/tools/libs/light/libxl_create.c
> @@ -510,7 +510,7 @@ int libxl__domain_build(libxl__gc *gc,
>       struct timeval start_time;
>       int i, ret;
>   
> -    ret = libxl__build_pre(gc, domid, d_config, state);
> +    ret = libxl__build_pre(gc, domid, d_config, state, false);
Instead of adding a parameter to libxl__build_pre() I'd rather add another
bool "soft_reset" to libxl__domain_build_state.

This would be more similar to the libxl__domain_build_state->restore use
case.


Juergen

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