6.1-stable review patch. If anyone has any objections, please let me know.
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From: Juergen Gross jgross@suse.com
[ Upstream commit db2832309a82b9acc4b8cc33a1831d36507ec13e ]
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 Link: https://lore.kernel.org/r/20231124074852.25161-1-jgross@suse.com Signed-off-by: Juergen Gross jgross@suse.com Signed-off-by: Sasha Levin sashal@kernel.org --- 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 0337392a31214..3c61bb98c10e2 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 a10903785a338..b2b2f4315b78d 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);