Messages in this thread | | | Date | Mon, 27 Nov 2023 16:00:17 +0100 | Subject | Re: [PATCH] x86/xen: fix percpu vcpu_info allocation | From | Jan Beulich <> |
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On 27.11.2023 15:57, Boris Ostrovsky wrote: > > > On 11/24/23 2:48 AM, Juergen Gross wrote: >> Today the percpu struct vcpu_info is allocated via DEFINE_PER_CPU(), >> meaning that it could cross a page boundary. In this case registering >> it with the hypervisor will fail, resulting in a panic(). >> >> This can easily be fixed by using DEFINE_PER_CPU_ALIGNED() instead, >> as struct vcpu_info is guaranteed to have a size of 64 bytes, matching >> the cache line size of x86 64-bit processors (Xen doesn't support >> 32-bit processors). >> >> Fixes: 5ead97c84fa7 ("xen: Core Xen implementation") >> Signed-off-by: Juergen Gross <jgross@suse.com> > > Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.con> > > although I am not sure in usefulness of BUILD_BUG_ON --- 64 bytes is part of ABI and hypervisor already has its own BUILD_BUG_ON for this.
I understood the check to guard against SMP_CACHE_BYTES < 64.
Jan
>> @@ -160,6 +163,7 @@ void xen_vcpu_setup(int cpu) >> int err; >> struct vcpu_info *vcpup; >> >> + BUILD_BUG_ON(sizeof(*vcpup) > SMP_CACHE_BYTES); >> BUG_ON(HYPERVISOR_shared_info == &xen_dummy_shared_info); >
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