WSL2-Linux-Kernel/arch/x86/xen/smp_hvm.c

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#include <asm/smp.h>
xen: Revert commits da72ff5bfcb0 and 72a9b186292d 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>
2017-04-24 22:04:53 +03:00
#include <xen/events.h>
#include "xen-ops.h"
#include "smp.h"
static void __init xen_hvm_smp_prepare_boot_cpu(void)
{
BUG_ON(smp_processor_id() != 0);
native_smp_prepare_boot_cpu();
/*
* Setup vcpu_info for boot CPU. Secondary CPUs get their vcpu_info
* in xen_cpu_up_prepare_hvm().
*/
xen_vcpu_setup(0);
/*
* The alternative logic (which patches the unlock/lock) runs before
* the smp bootup up code is activated. Hence we need to set this up
* the core kernel is being patched. Otherwise we will have only
* modules patched but not core code.
*/
xen_init_spinlocks();
}
static void __init xen_hvm_smp_prepare_cpus(unsigned int max_cpus)
{
xen/pvh*: Support > 32 VCPUs at domain restore 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>
2017-06-03 03:05:59 +03:00
int cpu;
native_smp_prepare_cpus(max_cpus);
WARN_ON(xen_smp_intr_init(0));
xen_init_lock_cpu(0);
xen/pvh*: Support > 32 VCPUs at domain restore 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>
2017-06-03 03:05:59 +03:00
for_each_possible_cpu(cpu) {
if (cpu == 0)
continue;
/* Set default vcpu_id to make sure that we don't use cpu-0's */
per_cpu(xen_vcpu_id, cpu) = XEN_VCPU_ID_INVALID;
}
}
#ifdef CONFIG_HOTPLUG_CPU
static void xen_hvm_cpu_die(unsigned int cpu)
{
if (common_cpu_die(cpu) == 0) {
xen_smp_intr_free(cpu);
xen_uninit_lock_cpu(cpu);
xen_teardown_timer(cpu);
}
}
#else
static void xen_hvm_cpu_die(unsigned int cpu)
{
BUG();
}
#endif
void __init xen_hvm_smp_init(void)
{
xen: Revert commits da72ff5bfcb0 and 72a9b186292d 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>
2017-04-24 22:04:53 +03:00
if (!xen_have_vector_callback)
return;
smp_ops.smp_prepare_cpus = xen_hvm_smp_prepare_cpus;
smp_ops.smp_send_reschedule = xen_smp_send_reschedule;
smp_ops.cpu_die = xen_hvm_cpu_die;
smp_ops.send_call_func_ipi = xen_smp_send_call_function_ipi;
smp_ops.send_call_func_single_ipi = xen_smp_send_call_function_single_ipi;
smp_ops.smp_prepare_boot_cpu = xen_hvm_smp_prepare_boot_cpu;
smp_ops.smp_cpus_done = xen_smp_cpus_done;
}