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Peter Anvin" , xen-devel@lists.xenproject.org Subject: [PATCH] x86/xen: fix percpu vcpu_info allocation Date: Fri, 24 Nov 2023 08:48:52 +0100 Message-Id: <20231124074852.25161-1-jgross@suse.com> X-Mailer: git-send-email 2.35.3 MIME-Version: 1.0 Authentication-Results: smtp-out1.suse.de; none X-Spamd-Result: default: False [4.70 / 50.00]; ARC_NA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; R_MISSING_CHARSET(2.50)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; MIME_GOOD(-0.10)[text/plain]; BROKEN_CONTENT_TYPE(1.50)[]; RCVD_COUNT_THREE(0.00)[3]; DKIM_SIGNED(0.00)[suse.com:s=susede1]; NEURAL_HAM_SHORT(-0.20)[-1.000]; RCPT_COUNT_SEVEN(0.00)[10]; MID_CONTAINS_FROM(1.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.com:email]; FUZZY_BLOCKED(0.00)[rspamd.com]; FROM_EQ_ENVFROM(0.00)[]; MIME_TRACE(0.00)[0:+]; RCVD_TLS_ALL(0.00)[]; BAYES_HAM(-0.00)[40.20%] 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 Reviewed-by: Boris Ostrovsky --- arch/x86/xen/enlighten.c | 6 +++++- arch/x86/xen/xen-ops.h | 2 +- 2 files changed, 6 insertions(+), 2 deletions(-) diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c index 0337392a3121..3c61bb98c10e 100644 --- a/arch/x86/xen/enlighten.c +++ b/arch/x86/xen/enlighten.c @@ -33,9 +33,12 @@ EXPORT_SYMBOL_GPL(hypercall_page); * and xen_vcpu_setup for details. By default it points to share_info->vcpu_info * but during boot it is switched to point to xen_vcpu_info. * The pointer is used in xen_evtchn_do_upcall to acknowledge pending events. + * Make sure that xen_vcpu_info doesn't cross a page boundary by making it + * cache-line aligned (the struct is guaranteed to have a size of 64 bytes, + * which matches the cache line size of 64-bit x86 processors). */ DEFINE_PER_CPU(struct vcpu_info *, xen_vcpu); -DEFINE_PER_CPU(struct vcpu_info, xen_vcpu_info); +DEFINE_PER_CPU_ALIGNED(struct vcpu_info, xen_vcpu_info); /* Linux <-> Xen vCPU id mapping */ DEFINE_PER_CPU(uint32_t, xen_vcpu_id); @@ -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); /* diff --git a/arch/x86/xen/xen-ops.h b/arch/x86/xen/xen-ops.h index 408a2aa66c69..a87ab36889e7 100644 --- a/arch/x86/xen/xen-ops.h +++ b/arch/x86/xen/xen-ops.h @@ -21,7 +21,7 @@ extern void *xen_initial_gdt; struct trap_info; void xen_copy_trap_info(struct trap_info *traps); -DECLARE_PER_CPU(struct vcpu_info, xen_vcpu_info); +DECLARE_PER_CPU_ALIGNED(struct vcpu_info, xen_vcpu_info); DECLARE_PER_CPU(unsigned long, xen_cr3); DECLARE_PER_CPU(unsigned long, xen_current_cr3);