On 08/01/2020 12:18, Jürgen Groß wrote: > On 08.01.20 13:16, Wei Liu wrote: >> On Wed, Jan 08, 2020 at 12:01:48PM +0100, Juergen Gross wrote: >>> cpu_smpboot_free() removes the stubs for the cpu going offline, but it >>> isn't clearing the related percpu variables. This will result in >>> crashes when a stub page is released due to all related cpus gone >>> offline and one of those cpus going online later. >>> >>> Fix that by clearing stubs.addr and stubs.mfn in order to allocate a >>> new stub page when needed. >>> >>> Signed-off-by: Juergen Gross <jgr...@suse.com> >>> --- >>> xen/arch/x86/smpboot.c | 2 ++ >>> 1 file changed, 2 insertions(+) >>> >>> diff --git a/xen/arch/x86/smpboot.c b/xen/arch/x86/smpboot.c >>> index 7e29704080..46c0729214 100644 >>> --- a/xen/arch/x86/smpboot.c >>> +++ b/xen/arch/x86/smpboot.c >>> @@ -945,6 +945,8 @@ static void cpu_smpboot_free(unsigned int cpu, >>> bool remove) >>> (per_cpu(stubs.addr, cpu) | >>> ~PAGE_MASK) + 1); >>> if ( i == STUBS_PER_PAGE ) >>> free_domheap_page(mfn_to_page(mfn)); >>> + per_cpu(stubs.addr, cpu) = 0; >>> + per_cpu(stubs.mfn, cpu) = 0; >> >> Shouldn't the mfn be set to INVALID_MFN instead? > > This would require modifying alloc_stub_page(): > > if ( *mfn ) > pg = mfn_to_page(_mfn(*mfn)); > else
Correct. per-cpu data is initialised to 0, not to a custom default, so using INVALID_MFN is more complicated. ~Andrew _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
