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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v9 15/20] x86/VPMU: Handle PMU interrupts for PV guests
Add support for handling PMU interrupts for PV guests.
VPMU for the interrupted VCPU is unloaded until the guest issues XENPMU_flush
hypercall. This allows the guest to access PMU MSR values that are stored in
VPMU context which is shared between hypervisor and domain, thus avoiding
traps to hypervisor.
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
Acked-by: Kevin Tian <kevin.tian@xxxxxxxxx>
Reviewed-by: Dietmar Hahn <dietmar.hahn@xxxxxxxxxxxxxx>
Tested-by: Dietmar Hahn <dietmar.hahn@xxxxxxxxxxxxxx>
---
xen/arch/x86/hvm/vpmu.c | 158 +++++++++++++++++++++++++++++++++++++++++++----
xen/include/public/pmu.h | 7 +++
2 files changed, 153 insertions(+), 12 deletions(-)
diff --git a/xen/arch/x86/hvm/vpmu.c b/xen/arch/x86/hvm/vpmu.c
index 399e195..818f721 100644
--- a/xen/arch/x86/hvm/vpmu.c
+++ b/xen/arch/x86/hvm/vpmu.c
@@ -80,44 +80,167 @@ static void __init parse_vpmu_param(char *s)
void vpmu_lvtpc_update(uint32_t val)
{
- struct vpmu_struct *vpmu = vcpu_vpmu(current);
+ struct vcpu *curr = current;
+ struct vpmu_struct *vpmu = vcpu_vpmu(curr);
vpmu->hw_lapic_lvtpc = PMU_APIC_VECTOR | (val & APIC_LVT_MASKED);
- apic_write(APIC_LVTPC, vpmu->hw_lapic_lvtpc);
+
+ /* Postpone APIC updates for PV(H) guests if PMU interrupt is pending */
+ if ( is_hvm_domain(curr->domain) ||
+ !(vpmu->xenpmu_data && (vpmu->xenpmu_data->pmu_flags & PMU_CACHED)) )
+ apic_write(APIC_LVTPC, vpmu->hw_lapic_lvtpc);
}
int vpmu_do_wrmsr(unsigned int msr, uint64_t msr_content)
{
- struct vpmu_struct *vpmu = vcpu_vpmu(current);
+ struct vcpu *curr = current;
+ struct vpmu_struct *vpmu = vcpu_vpmu(curr);
if ( !(vpmu_mode & XENPMU_MODE_SELF) )
return 0;
if ( vpmu->arch_vpmu_ops && vpmu->arch_vpmu_ops->do_wrmsr )
- return vpmu->arch_vpmu_ops->do_wrmsr(msr, msr_content);
+ {
+ int ret = vpmu->arch_vpmu_ops->do_wrmsr(msr, msr_content);
+
+ /*
+ * We may have received a PMU interrupt during WRMSR handling
+ * and since do_wrmsr may load VPMU context we should save
+ * (and unload) it again.
+ */
+ if ( !is_hvm_domain(curr->domain) &&
+ vpmu->xenpmu_data && (vpmu->xenpmu_data->pmu_flags & PMU_CACHED) )
+ {
+ vpmu_set(vpmu, VPMU_CONTEXT_SAVE);
+ vpmu->arch_vpmu_ops->arch_vpmu_save(curr);
+ vpmu_reset(vpmu, VPMU_CONTEXT_SAVE | VPMU_CONTEXT_LOADED);
+ }
+ return ret;
+ }
return 0;
}
int vpmu_do_rdmsr(unsigned int msr, uint64_t *msr_content)
{
- struct vpmu_struct *vpmu = vcpu_vpmu(current);
+ struct vcpu *curr = current;
+ struct vpmu_struct *vpmu = vcpu_vpmu(curr);
if ( !(vpmu_mode & XENPMU_MODE_SELF) )
return 0;
if ( vpmu->arch_vpmu_ops && vpmu->arch_vpmu_ops->do_rdmsr )
- return vpmu->arch_vpmu_ops->do_rdmsr(msr, msr_content);
+ {
+ int ret = vpmu->arch_vpmu_ops->do_rdmsr(msr, msr_content);
+
+ if ( !is_hvm_domain(curr->domain) &&
+ vpmu->xenpmu_data && (vpmu->xenpmu_data->pmu_flags & PMU_CACHED) )
+ {
+ vpmu_set(vpmu, VPMU_CONTEXT_SAVE);
+ vpmu->arch_vpmu_ops->arch_vpmu_save(curr);
+ vpmu_reset(vpmu, VPMU_CONTEXT_SAVE | VPMU_CONTEXT_LOADED);
+ }
+ return ret;
+ }
return 0;
}
+static struct vcpu *choose_hwdom_vcpu(void)
+{
+ struct vcpu *v;
+ unsigned idx = smp_processor_id() % hardware_domain->max_vcpus;
+
+ if ( hardware_domain->vcpu == NULL )
+ return NULL;
+
+ v = hardware_domain->vcpu[idx];
+
+ /*
+ * If index is not populated search downwards the vcpu array until
+ * a valid vcpu can be found
+ */
+ while ( !v && idx-- )
+ v = hardware_domain->vcpu[idx];
+
+ return v;
+}
+
int vpmu_do_interrupt(struct cpu_user_regs *regs)
{
- struct vcpu *v = current;
- struct vpmu_struct *vpmu = vcpu_vpmu(v);
+ struct vcpu *sampled = current, *sampling;
+ struct vpmu_struct *vpmu;
+
+ /* dom0 will handle interrupt for special domains (e.g. idle domain) */
+ if ( sampled->domain->domain_id >= DOMID_FIRST_RESERVED )
+ {
+ sampling = choose_hwdom_vcpu();
+ if ( !sampling )
+ return 0;
+ }
+ else
+ sampling = sampled;
+
+ vpmu = vcpu_vpmu(sampling);
+ if ( !is_hvm_domain(sampling->domain) )
+ {
+ /* PV(H) guest or dom0 is doing system profiling */
+ const struct cpu_user_regs *gregs;
+
+ if ( !vpmu->xenpmu_data )
+ return 0;
+
+ if ( vpmu->xenpmu_data->pmu_flags & PMU_CACHED )
+ return 1;
+
+ if ( is_pvh_domain(sampled->domain) &&
+ !vpmu->arch_vpmu_ops->do_interrupt(regs) )
+ return 0;
+
+ /* PV guest will be reading PMU MSRs from xenpmu_data */
+ vpmu_set(vpmu, VPMU_CONTEXT_SAVE | VPMU_CONTEXT_LOADED);
+ vpmu->arch_vpmu_ops->arch_vpmu_save(sampling);
+ vpmu_reset(vpmu, VPMU_CONTEXT_SAVE | VPMU_CONTEXT_LOADED);
+
+ /* Store appropriate registers in xenpmu_data */
+ if ( is_pv_32bit_domain(sampled->domain) )
+ {
+ /*
+ * 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.
+ */
+ struct compat_cpu_user_regs *cmp;
+
+ gregs = guest_cpu_user_regs();
+
+ cmp = (void *)&vpmu->xenpmu_data->pmu.r.regs;
+ XLAT_cpu_user_regs(cmp, gregs);
+ }
+ else if ( !is_hardware_domain(sampled->domain) &&
+ !is_idle_vcpu(sampled) )
+ {
+ /* PV(H) guest */
+ gregs = guest_cpu_user_regs();
+ vpmu->xenpmu_data->pmu.r.regs = *gregs;
+ }
+ else
+ vpmu->xenpmu_data->pmu.r.regs = *regs;
+
+ vpmu->xenpmu_data->domain_id = sampled->domain->domain_id;
+ vpmu->xenpmu_data->vcpu_id = sampled->vcpu_id;
+ vpmu->xenpmu_data->pcpu_id = smp_processor_id();
+
+ vpmu->xenpmu_data->pmu_flags |= PMU_CACHED;
+ apic_write(APIC_LVTPC, vpmu->hw_lapic_lvtpc | APIC_LVT_MASKED);
+ vpmu->hw_lapic_lvtpc |= APIC_LVT_MASKED;
+
+ send_guest_vcpu_virq(sampling, VIRQ_XENPMU);
+
+ return 1;
+ }
if ( vpmu->arch_vpmu_ops )
{
- struct vlapic *vlapic = vcpu_vlapic(v);
+ struct vlapic *vlapic = vcpu_vlapic(sampling);
u32 vlapic_lvtpc;
unsigned char int_vec;
@@ -131,9 +254,9 @@ int vpmu_do_interrupt(struct cpu_user_regs *regs)
int_vec = vlapic_lvtpc & APIC_VECTOR_MASK;
if ( GET_APIC_DELIVERY_MODE(vlapic_lvtpc) == APIC_MODE_FIXED )
- vlapic_set_irq(vcpu_vlapic(v), int_vec, 0);
+ vlapic_set_irq(vcpu_vlapic(sampling), int_vec, 0);
else
- v->nmi_pending = 1;
+ sampling->nmi_pending = 1;
return 1;
}
@@ -232,7 +355,9 @@ void vpmu_load(struct vcpu *v)
local_irq_enable();
/* Only when PMU is counting, we load PMU context immediately. */
- if ( !vpmu_is_set(vpmu, VPMU_RUNNING) )
+ if ( !vpmu_is_set(vpmu, VPMU_RUNNING) ||
+ (!is_hvm_domain(v->domain) &&
+ vpmu->xenpmu_data->pmu_flags & PMU_CACHED) )
return;
if ( vpmu->arch_vpmu_ops && vpmu->arch_vpmu_ops->arch_vpmu_load )
@@ -436,6 +561,7 @@
vpmu_force_context_switch(XEN_GUEST_HANDLE_PARAM(xen_pmu_params_t) arg)
long do_xenpmu_op(int op, XEN_GUEST_HANDLE_PARAM(xen_pmu_params_t) arg)
{
int ret = -EINVAL;
+ struct vcpu *curr;
xen_pmu_params_t pmu_params;
switch ( op )
@@ -532,6 +658,14 @@ long do_xenpmu_op(int op,
XEN_GUEST_HANDLE_PARAM(xen_pmu_params_t) arg)
vpmu_lvtpc_update(current->arch.vpmu.xenpmu_data->pmu.l.lapic_lvtpc);
ret = 0;
break;
+
+ case XENPMU_flush:
+ curr = current;
+ curr->arch.vpmu.xenpmu_data->pmu_flags &= ~PMU_CACHED;
+ vpmu_lvtpc_update(curr->arch.vpmu.xenpmu_data->pmu.l.lapic_lvtpc);
+ vpmu_load(curr);
+ ret = 0;
+ break;
}
return ret;
diff --git a/xen/include/public/pmu.h b/xen/include/public/pmu.h
index 92f3683..44bf43f 100644
--- a/xen/include/public/pmu.h
+++ b/xen/include/public/pmu.h
@@ -28,6 +28,7 @@
#define XENPMU_init 4
#define XENPMU_finish 5
#define XENPMU_lvtpc_set 6
+#define XENPMU_flush 7 /* Write cached MSR values to HW */
/* ` } */
/* Parameters structure for HYPERVISOR_xenpmu_op call */
@@ -59,6 +60,12 @@ DEFINE_XEN_GUEST_HANDLE(xen_pmu_params_t);
*/
#define XENPMU_FEATURE_INTEL_BTS 1
+/*
+ * PMU MSRs are cached in the context so the PV guest doesn't need to trap to
+ * the hypervisor
+ */
+#define PMU_CACHED 1
+
/* Shared between hypervisor and PV domain */
struct xen_pmu_data {
uint32_t domain_id;
--
1.8.1.4
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