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* xen/vcpu: Handle xen_vcpu_setup() failure at bootAnkur Arora2017-06-131-0/+1
| | | | | | | | | | | | | | | | | On PVH, PVHVM, at failure in the VCPUOP_register_vcpu_info hypercall we limit the number of cpus to to MAX_VIRT_CPUS. However, if this failure had occurred for a cpu beyond MAX_VIRT_CPUS, we continue to function with > MAX_VIRT_CPUS. This leads to problems at the next save/restore cycle when there are > MAX_VIRT_CPUS threads going into stop_machine() but coming back up there's valid state for only the first MAX_VIRT_CPUS. This patch pulls the excess CPUs down via cpu_down(). Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Signed-off-by: Ankur Arora <ankur.a.arora@oracle.com> Signed-off-by: Juergen Gross <jgross@suse.com>
* xen/pvh*: Support > 32 VCPUs at domain restoreAnkur Arora2017-06-131-0/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When Xen restores a PVHVM or PVH guest, its shared_info only holds up to 32 CPUs. The hypercall VCPUOP_register_vcpu_info allows us to setup per-page areas for VCPUs. This means we can boot PVH* guests with more than 32 VCPUs. During restore the per-cpu structure is allocated freshly by the hypervisor (vcpu_info_mfn is set to INVALID_MFN) so that the newly restored guest can make a VCPUOP_register_vcpu_info hypercall. However, we end up triggering this condition in Xen: /* Run this command on yourself or on other offline VCPUS. */ if ( (v != current) && !test_bit(_VPF_down, &v->pause_flags) ) which means we are unable to setup the per-cpu VCPU structures for running VCPUS. The Linux PV code paths makes this work by iterating over cpu_possible in xen_vcpu_restore() with: 1) is target CPU up (VCPUOP_is_up hypercall?) 2) if yes, then VCPUOP_down to pause it 3) VCPUOP_register_vcpu_info 4) if it was down, then VCPUOP_up to bring it back up With Xen commit 192df6f9122d ("xen/x86: allow HVM guests to use hypercalls to bring up vCPUs") this is available for non-PV guests. As such first check if VCPUOP_is_up is actually possible before trying this dance. As most of this dance code is done already in xen_vcpu_restore() let's make it callable on PV, PVH and PVHVM. Based-on-patch-by: Konrad Wilk <konrad.wilk@oracle.com> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Signed-off-by: Ankur Arora <ankur.a.arora@oracle.com> Signed-off-by: Juergen Gross <jgross@suse.com>
* xen/vcpu: Simplify xen_vcpu related codeAnkur Arora2017-06-131-1/+2
| | | | | | | | | | | | | | | | | Largely mechanical changes to aid unification of xen_vcpu_restore() logic for PV, PVH and PVHVM. xen_vcpu_setup(): the only change in logic is that clamp_max_cpus() is now handled inside the "if (!xen_have_vcpu_info_placement)" block. xen_vcpu_restore(): code movement from enlighten_pv.c to enlighten.c. xen_vcpu_info_reset(): pulls together all the code where xen_vcpu is set to default. Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Signed-off-by: Ankur Arora <ankur.a.arora@oracle.com> Signed-off-by: Juergen Gross <jgross@suse.com>
* xen: Revert commits da72ff5bfcb0 and 72a9b186292dBoris Ostrovsky2017-05-021-0/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Recent discussion (http://marc.info/?l=xen-devel&m=149192184523741) established that commit 72a9b186292d ("xen: Remove event channel notification through Xen PCI platform device") (and thus commit da72ff5bfcb0 ("partially revert "xen: Remove event channel notification through Xen PCI platform device"")) are unnecessary and, in fact, prevent HVM guests from booting on Xen releases prior to 4.0 Therefore we revert both of those commits. The summary of that discussion is below: Here is the brief summary of the current situation: Before the offending commit (72a9b186292): 1) INTx does not work because of the reset_watches path. 2) The reset_watches path is only taken if you have Xen > 4.0 3) The Linux Kernel by default will use vector inject if the hypervisor support. So even INTx does not work no body running the kernel with Xen > 4.0 would notice. Unless he explicitly disabled this feature either in the kernel or in Xen (and this can only be disabled by modifying the code, not user-supported way to do it). After the offending commit (+ partial revert): 1) INTx is no longer support for HVM (only for PV guests). 2) Any HVM guest The kernel will not boot on Xen < 4.0 which does not have vector injection support. Since the only other mode supported is INTx which. So based on this summary, I think before commit (72a9b186292) we were in much better position from a user point of view. Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Reviewed-by: Juergen Gross <jgross@suse.com> Signed-off-by: Juergen Gross <jgross@suse.com>
* x86/xen: split off smp_hvm.cVitaly Kuznetsov2017-05-021-0/+58
Move PVHVM related code to smp_hvm.c. Drop 'static' qualifier from xen_smp_send_reschedule(), xen_smp_send_call_function_ipi(), xen_smp_send_call_function_single_ipi(), these functions will be moved to common smp code when smp_pv.c is split. Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Reviewed-by: Juergen Gross <jgross@suse.com> Signed-off-by: Juergen Gross <jgross@suse.com>