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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v3 1/1] Introduce VCPUOP_reset_vcpu_info
When an SMP guest performs kexec/kdump it tries issuing
VCPUOP_register_vcpu_info.
This fails due to vcpu_info already being registered. Introduce new vcpu
operation
to reset vcpu_info to its default state.
Based on the original patch by Konrad Rzeszutek Wilk.
Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
---
Changes from RFCv2:
- modify unmap_vcpu_info() to match both needs [Jan Beulich]
- support VCPUOP_reset_vcpu_info for current VCPU [Jan Beulich]
- improve description in public/vcpu.h [Jan Beulich]
Changes from RFCv1:
- Don't use unsuitable unmap_vcpu_info(), rewrite [Jan Beulich]
- Require FIFO ABI being in 2-level mode
- Describe limitations in include/public/vcpu.h [Jan Beulich]
---
xen/arch/x86/hvm/hvm.c | 1 +
xen/common/domain.c | 73 +++++++++++++++++++++++++++++++++++++++++------
xen/include/public/vcpu.h | 19 ++++++++++++
3 files changed, 85 insertions(+), 8 deletions(-)
diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index 216c3f2..7917272 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -3332,6 +3332,7 @@ static long hvm_vcpu_op(
case VCPUOP_set_singleshot_timer:
case VCPUOP_stop_singleshot_timer:
case VCPUOP_register_vcpu_info:
+ case VCPUOP_reset_vcpu_info:
case VCPUOP_register_vcpu_time_memory_area:
rc = do_vcpu_op(cmd, vcpuid, arg);
break;
diff --git a/xen/common/domain.c b/xen/common/domain.c
index 44e5cbe..9e10e1e 100644
--- a/xen/common/domain.c
+++ b/xen/common/domain.c
@@ -956,25 +956,52 @@ int map_vcpu_info(struct vcpu *v, unsigned long gfn,
unsigned offset)
}
/*
- * Unmap the vcpu info page if the guest decided to place it somewhere
- * else. This is only used from arch_domain_destroy, so there's no
- * need to do anything clever.
+ * Unmap the vcpu info page if the guest decided to place it somewhere else.
+ * There's no need to do anything clever when the domain is dying (when called
+ * from arch_domain_destroy) and we need to prepare for rebinding when it is
not
+ * (in case VCPUOP_reset_vcpu_info was called).
*/
void unmap_vcpu_info(struct vcpu *v)
{
+ struct domain *d = v->domain;
unsigned long mfn;
+ vcpu_info_t *old_info;
+ unsigned int i;
+
+ mfn = v->vcpu_info_mfn;
+ old_info = v->vcpu_info;
- if ( v->vcpu_info_mfn == INVALID_MFN )
+ if ( mfn == INVALID_MFN )
return;
- mfn = v->vcpu_info_mfn;
+ if ( (!d->is_dying) && (v->vcpu_id < XEN_LEGACY_MAX_VCPUS) )
+ {
+ memcpy(&shared_info(d, vcpu_info[v->vcpu_id]), v->vcpu_info,
+ sizeof(vcpu_info_t));
+ v->vcpu_info = (vcpu_info_t *)&shared_info(d, vcpu_info[v->vcpu_id]);
+ }
+ else
+ v->vcpu_info = &dummy_vcpu_info;
unmap_domain_page_global((void *)
- ((unsigned long)v->vcpu_info & PAGE_MASK));
+ ((unsigned long)old_info & PAGE_MASK));
- v->vcpu_info = &dummy_vcpu_info;
+ put_page_and_type(mfn_to_page(mfn));
v->vcpu_info_mfn = INVALID_MFN;
- put_page_and_type(mfn_to_page(mfn));
+ if ( (!d->is_dying) && (v->vcpu_id < XEN_LEGACY_MAX_VCPUS) &&
+ (test_bit(_VPF_down, &v->pause_flags)) )
+ {
+ /* Make sure vcpu_info was set */
+ smp_wmb();
+
+ /*
+ * Mark everything as being pending for all offline VCPUs to make sure
+ * nothing gets lost when this VCPU goes online again.
+ */
+ vcpu_info(v, evtchn_upcall_pending) = 1;
+ for ( i = 0; i < BITS_PER_EVTCHN_WORD(d); i++ )
+ set_bit(i, &vcpu_info(v, evtchn_pending_sel));
+ }
}
long do_vcpu_op(int cmd, int vcpuid, XEN_GUEST_HANDLE_PARAM(void) arg)
@@ -1116,6 +1143,36 @@ long do_vcpu_op(int cmd, int vcpuid,
XEN_GUEST_HANDLE_PARAM(void) arg)
break;
}
+ case VCPUOP_reset_vcpu_info:
+ {
+
+ if ( (v != current) && !test_bit(_VPF_down, &v->pause_flags) )
+ {
+ printk(XENLOG_G_WARNING "%pv: VCPU is up or not current,"
+ "refusing to reset vcpu_info!\n", v);
+ return -EBUSY;
+ }
+
+ if ( v->evtchn_fifo )
+ {
+ printk(XENLOG_G_WARNING "%pv: FIFO evtchn ABI is being used,"
+ "refusing to reset vcpu_info!\n", v);
+ return -EBUSY;
+ }
+
+ if ( v->vcpu_info_mfn == INVALID_MFN )
+ {
+ rc = 0;
+ break;
+ }
+
+ domain_lock(d);
+ unmap_vcpu_info(v);
+ domain_unlock(d);
+ rc = 0;
+ break;
+ }
+
case VCPUOP_register_runstate_memory_area:
{
struct vcpu_register_runstate_memory_area area;
diff --git a/xen/include/public/vcpu.h b/xen/include/public/vcpu.h
index e888daf..c4d166c 100644
--- a/xen/include/public/vcpu.h
+++ b/xen/include/public/vcpu.h
@@ -227,6 +227,25 @@ struct vcpu_register_time_memory_area {
typedef struct vcpu_register_time_memory_area vcpu_register_time_memory_area_t;
DEFINE_XEN_GUEST_HANDLE(vcpu_register_time_memory_area_t);
+/*
+ * Reset all of the vcpu_info information from their previous location
+ * to the default one used at bootup. The following prerequisites should be
met:
+ * 1. Domain should be using 2-level event channel ABI. In case another
+ * non-default ABI is in use the domain is supposed to switch back to
+ * 2-level ABI with EVTCHNOP_reset.
+ * 2. The operation is unsupported for non-current online VCPUs. If performed
+ * during shutdown/kexec/... a guest domain is supposed to behave in the
+ * following sequence:
+ * - Choose special 'shutdown' VCPU, bring all other VCPUs down;
+ * - Issue VCPUOP_reset_vcpu_info for all offline VCPUs;
+ * - Issue VCPUOP_reset_vcpu_info for the 'shutdown' VCPU.
+ *
+ * After the call vcpu_info is reset to its default state: first
+ * XEN_LEGACY_MAX_VCPUS VCPUs will get it switched to shared_info and all other
+ * VCPUs will get dummy_vcpu_info.
+ */
+#define VCPUOP_reset_vcpu_info 14
+
#endif /* __XEN_PUBLIC_VCPU_H__ */
/*
--
1.9.3
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