On 20.09.13 at 11:42, Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx> wrote:
Add support for handling PMU interrupts for PV guests, make these interrupts
NMI instead of PMU_APIC_VECTOR vector. Depending on vpmu_mode forward the
interrupts to appropriate guest (mode is VPMU_ON) or to dom0 (VPMU_DOM0).
Is using NMIs here a necessity? I guess not, in which case I'd really
like this to be a (perhaps even non-default) option controllable via
command line option.
- * This interrupt handles performance counters interrupt
- */
-
-void pmu_apic_interrupt(struct cpu_user_regs *regs)
-{
- ack_APIC_irq();
- vpmu_do_interrupt(regs);
-}
So this was the only caller of vpmu_do_interrupt(); no new one gets
added in this patch afaics, and I don't recall having seen addition of
another caller in earlier patches. What's the deal?
@@ -99,17 +106,97 @@ int vpmu_do_rdmsr(unsigned int msr, uint64_t *msr_content)
int vpmu_do_interrupt(struct cpu_user_regs *regs)
{
struct vcpu *v = current;
- struct vpmu_struct *vpmu = vcpu_vpmu(v);
+ struct vpmu_struct *vpmu;
- if ( vpmu->arch_vpmu_ops )
+
+ /* dom0 will handle this interrupt */
+ if ( (vpmu_mode & XENPMU_MODE_PRIV) ||
+ (v->domain->domain_id >= DOMID_FIRST_RESERVED) )
+ {
+ if ( smp_processor_id() >= dom0->max_vcpus )
+ return 0;
+ v = dom0->vcpu[smp_processor_id()];
+ }
+
+ vpmu = vcpu_vpmu(v);
+ if ( !vpmu_is_set(vpmu, VPMU_CONTEXT_ALLOCATED) )
+ return 0;
+
+ if ( !is_hvm_domain(v->domain) || (vpmu_mode & XENPMU_MODE_PRIV) )
+ {
+ /* PV guest or dom0 is doing system profiling */
+ void *p;
+ struct cpu_user_regs *gregs;
+
+ p = &v->arch.vpmu.xenpmu_data->pmu.regs;
+
+ /* PV guest will be reading PMU MSRs from xenpmu_data */
+ vpmu_save_force(v);
+
+ /* Store appropriate registers in xenpmu_data
+ *
+ * Note: '!current->is_running' is possible when 'set_current(next)'
+ * for the (HVM) guest has been called but 'reset_stack_and_jump()'
+ * has not (i.e. the guest is not actually running yet).
+ */
+ if ( !is_hvm_domain(current->domain) ||
+ ((vpmu_mode & XENPMU_MODE_PRIV) && !current->is_running) )
+ {
+ /*
+ * 32-bit dom0 cannot process Xen's addresses (which are 64 bit)
+ * and therefore we treat it the same way as a non-priviledged
+ * PV 32-bit domain.
+ */
+ if ( is_pv_32bit_domain(current->domain) )
+ {
+ struct compat_cpu_user_regs cmp;
+
+ gregs = guest_cpu_user_regs();
+ XLAT_cpu_user_regs(&cmp, gregs);
+ memcpy(p, &cmp, sizeof(struct compat_cpu_user_regs));
+ }
+ else if ( (current->domain != dom0) && !is_idle_vcpu(current) &&
+ !(vpmu_mode & XENPMU_MODE_PRIV) )
+ {
+ /* PV guest */
+ gregs = guest_cpu_user_regs();
+ memcpy(p, gregs, sizeof(struct cpu_user_regs));
+ }
+ else
+ memcpy(p, regs, sizeof(struct cpu_user_regs));
+ }
+ else
+ {
+ /* HVM guest */
+ struct segment_register cs;
+
+ gregs = guest_cpu_user_regs();
+ hvm_get_segment_register(current, x86_seg_cs, &cs);
+ gregs->cs = cs.attr.fields.dpl;
+
+ memcpy(p, gregs, sizeof(struct cpu_user_regs));
+ }
+
+ v->arch.vpmu.xenpmu_data->domain_id = current->domain->domain_id;
+ v->arch.vpmu.xenpmu_data->vcpu_id = current->vcpu_id;
+ v->arch.vpmu.xenpmu_data->pcpu_id = smp_processor_id();
+
+ raise_softirq(PMU_SOFTIRQ);
+ vpmu_set(vpmu, VPMU_WAIT_FOR_FLUSH);
+
+ return 1;
+ }
+ else if ( vpmu->arch_vpmu_ops )
{
- struct vlapic *vlapic = vcpu_vlapic(v);
+ /* HVM guest */
+ struct vlapic *vlapic;
u32 vlapic_lvtpc;
unsigned char int_vec;
if ( !vpmu->arch_vpmu_ops->do_interrupt(regs) )
return 0;
+ vlapic = vcpu_vlapic(v);
if ( !is_vlapic_lvtpc_enabled(vlapic) )
return 1;
Assuming the plan is to run this in NMI context - this is _a lot_ of
stuff you want to do. Did you carefully audit all paths for being
NMI-safe?
Jan
