Re: [PATCH v2 1/2] libxl: Fix guest kexec - skip cpuid policy

[Anthony PERARD <anthony.perard@xxxxxxxxxx>]

On Mon, Jan 23, 2023 at 09:59:38PM -0500, 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

s/fixes/fixed/ or maybe better just write: "before commit 34990446ca91".

> have been ignored, so kexec would continue.
> 
> Fixes: 34990446ca91 "libxl: don't ignore the return value from 
> xc_cpuid_apply_policy"

FYI, the tags format is with () around the commit title:
    Fixes: 34990446ca91 ("libxl: don't ignore the return value from 
xc_cpuid_apply_policy")
I have this in my git config file to help generate those:
[alias]
    fixes = log -1 --abbrev=12 --format=tformat:'Fixes: %h (\"%s\")'


> Signed-off-by: Jason Andryuk <jandryuk@xxxxxxxxx>
> ---
> Probably a backport candidate since this has been broken for a while.
> 
> v2:
> Use soft_reset field in libxl__domain_build_state. - Juergen

Reviewed-by: Anthony PERARD <anthony.perard@xxxxxxxxxx>

Thanks,

-- 
Anthony PERARD