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x86/xen: fix percpu vcpu_info allocation

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[ 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: 5ead97c84f ("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>
This commit is contained in:
Juergen Gross 2023-11-24 08:48:52 +01:00 committed by Greg Kroah-Hartman
parent 00bc8b2cf4
commit b3b839fb63
2 changed files with 6 additions and 2 deletions
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6
arch/x86/xen/enlighten.c
View File

@ -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);
/*

2
arch/x86/xen/xen-ops.h
View File

@ -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);