From 774901788c5614798931a1cb2e20dd8b885f97ab Mon Sep 17 00:00:00 2001 From: Juergen Gross Date: Thu, 9 Jan 2020 11:07:38 +0100 Subject: [PATCH] x86: clear per cpu stub page information in cpu_smpboot_free() 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, irrespective of whether the CPU gets parked or removed. Fixes: 2e6c8f182c9c50 ("x86: distinguish CPU offlining from CPU removal") Signed-off-by: Juergen Gross Reviewed-by: Wei Liu Reviewed-by: Jan Beulich Tested-by: Tao Xu --- 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..301f746979 100644 --- a/xen/arch/x86/smpboot.c +++ b/xen/arch/x86/smpboot.c @@ -943,6 +943,8 @@ static void cpu_smpboot_free(unsigned int cpu, bool remove) unmap_domain_page(stub_page); destroy_xen_mappings(per_cpu(stubs.addr, cpu) & PAGE_MASK, (per_cpu(stubs.addr, cpu) | ~PAGE_MASK) + 1); + per_cpu(stubs.addr, cpu) = 0; + per_cpu(stubs.mfn, cpu) = 0; if ( i == STUBS_PER_PAGE ) free_domheap_page(mfn_to_page(mfn)); } -- 2.39.5