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| author | Vitaly Kuznetsov <vkuznets@redhat.com> | 2016-09-08 11:48:28 +0200 |
|---|---|---|
| committer | David Vrabel <david.vrabel@citrix.com> | 2016-09-14 14:39:13 +0100 |
| commit | de75abbe0121a6c3c9c6b04c75300088e57ad1d5 (patch) | |
| tree | def35bbb8678c3d1820fd730d73ae440c753057b /arch/arm/xen | |
| parent | 55467dea2967259f21f4f854fc99d39cc5fea60e (diff) | |
| download | linux-de75abbe0121a6c3c9c6b04c75300088e57ad1d5.tar.bz2 | |
arm/xen: fix SMP guests boot
Commit 88e957d6e47f ("xen: introduce xen_vcpu_id mapping") broke SMP
ARM guests on Xen. When FIFO-based event channels are in use (this is
the default), evtchn_fifo_alloc_control_block() is called on
CPU_UP_PREPARE event and this happens before we set up xen_vcpu_id
mapping in xen_starting_cpu. Temporary fix the issue by setting direct
Linux CPU id <-> Xen vCPU id mapping for all possible CPUs at boot. We
don't currently support kexec/kdump on Xen/ARM so these ids always
match.
In future, we have several ways to solve the issue, e.g.:
- Eliminate all hypercalls from CPU_UP_PREPARE, do them from the
starting CPU. This can probably be done for both x86 and ARM and, if
done, will allow us to get Xen's idea of vCPU id from CPUID/MPIDR on
the starting CPU directly, no messing with ACPI/device tree
required.
- Save vCPU id information from ACPI/device tree on ARM and use it to
initialize xen_vcpu_id mapping. This is the same trick we currently
do on x86.
Reported-by: Julien Grall <julien.grall@arm.com>
Tested-by: Wei Chen <Wei.Chen@arm.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Acked-by: Stefano Stabellini <sstabellini@kernel.org>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Diffstat (limited to 'arch/arm/xen')
| -rw-r--r-- | arch/arm/xen/enlighten.c | 7 |
1 files changed, 3 insertions, 4 deletions
diff --git a/arch/arm/xen/enlighten.c b/arch/arm/xen/enlighten.c index 3d2cef6488ea..f193414d0f6f 100644 --- a/arch/arm/xen/enlighten.c +++ b/arch/arm/xen/enlighten.c @@ -170,9 +170,6 @@ static int xen_starting_cpu(unsigned int cpu) pr_info("Xen: initializing cpu%d\n", cpu); vcpup = per_cpu_ptr(xen_vcpu_info, cpu); - /* Direct vCPU id mapping for ARM guests. */ - per_cpu(xen_vcpu_id, cpu) = cpu; - info.mfn = virt_to_gfn(vcpup); info.offset = xen_offset_in_page(vcpup); @@ -330,6 +327,7 @@ static int __init xen_guest_init(void) { struct xen_add_to_physmap xatp; struct shared_info *shared_info_page = NULL; + int cpu; if (!xen_domain()) return 0; @@ -380,7 +378,8 @@ static int __init xen_guest_init(void) return -ENOMEM; /* Direct vCPU id mapping for ARM guests. */ - per_cpu(xen_vcpu_id, 0) = 0; + for_each_possible_cpu(cpu) + per_cpu(xen_vcpu_id, cpu) = cpu; xen_auto_xlat_grant_frames.count = gnttab_max_grant_frames(); if (xen_xlate_map_ballooned_pages(&xen_auto_xlat_grant_frames.pfn, |