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authorVitaly Kuznetsov <vkuznets@redhat.com>2016-09-08 11:48:28 +0200
committerDavid Vrabel <david.vrabel@citrix.com>2016-09-14 14:39:13 +0100
commitde75abbe0121a6c3c9c6b04c75300088e57ad1d5 (patch)
treedef35bbb8678c3d1820fd730d73ae440c753057b
parent55467dea2967259f21f4f854fc99d39cc5fea60e (diff)
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>
-rw-r--r--arch/arm/xen/enlighten.c7
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,