[Xen-devel] [PATCH v11 for-xen-4.5 18/20] x86/VPMU: Add privileged PMU mode

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

Add support for privileged PMU mode (XENPMU_MODE_ALL) which allows privileged
domain (dom0) profile both itself (and the hypervisor) and the guests. While
this mode is on profiling in guests is disabled.

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
---
 xen/arch/x86/hvm/vpmu.c  | 26 ++++++++++++++++++--------
 xen/arch/x86/traps.c     | 12 ++++++++++++
 xen/include/public/pmu.h |  3 +++
 3 files changed, 33 insertions(+), 8 deletions(-)

diff --git a/xen/arch/x86/hvm/vpmu.c b/xen/arch/x86/hvm/vpmu.c
index 4a98a31..1e0575a 100644
--- a/xen/arch/x86/hvm/vpmu.c
+++ b/xen/arch/x86/hvm/vpmu.c
@@ -98,7 +98,9 @@ int vpmu_do_msr(unsigned int msr, uint64_t *msr_content,
     struct arch_vpmu_ops *ops;
     int ret = 0;
 
-    if ( !(vpmu_mode & (XENPMU_MODE_SELF | XENPMU_MODE_HV)) )
+    if ( (vpmu_mode == XENPMU_MODE_OFF) ||
+         ((vpmu_mode & XENPMU_MODE_ALL) &&
+          !is_hardware_domain(current->domain)) )
         return 0;
 
     curr = current;
@@ -153,8 +155,12 @@ int vpmu_do_interrupt(struct cpu_user_regs *regs)
     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 )
+    /*
+     * dom0 will handle interrupt for special domains (e.g. idle domain) or,
+     * in XENPMU_MODE_ALL, for everyone.
+     */
+    if ( (vpmu_mode & XENPMU_MODE_ALL) ||
+         (sampled->domain->domain_id >= DOMID_FIRST_RESERVED) )
     {
         sampling = choose_hwdom_vcpu();
         if ( !sampling )
@@ -164,7 +170,7 @@ int vpmu_do_interrupt(struct cpu_user_regs *regs)
         sampling = sampled;
 
     vpmu = vcpu_vpmu(sampling);
-    if ( !is_hvm_domain(sampling->domain) )
+    if ( !is_hvm_domain(sampling->domain) || (vpmu_mode & XENPMU_MODE_ALL) )
     {
         /* PV(H) guest */
         const struct cpu_user_regs *cur_regs;
@@ -176,6 +182,7 @@ int vpmu_do_interrupt(struct cpu_user_regs *regs)
             return 1;
 
         if ( is_pvh_domain(sampled->domain) &&
+             !(vpmu_mode & XENPMU_MODE_ALL) &&
              !vpmu->arch_vpmu_ops->do_interrupt(regs) )
             return 0;
 
@@ -218,7 +225,7 @@ int vpmu_do_interrupt(struct cpu_user_regs *regs)
             r->rip = cur_regs->rip;
             r->rsp = cur_regs->rsp;
 
-            if ( !is_pvh_domain(sampled->domain) )
+            if ( !has_hvm_container_domain(sampled->domain) )
             {
                 r->cs = cur_regs->cs;
                 if ( sampled->arch.flags & TF_kernel_mode )
@@ -233,7 +240,9 @@ int vpmu_do_interrupt(struct cpu_user_regs *regs)
             }
         }
 
-        vpmu->xenpmu_data->domain_id = DOMID_SELF;
+        vpmu->xenpmu_data->domain_id = (sampled == sampling) ?
+                                       DOMID_SELF :
+                                       sampled->domain->domain_id;
         vpmu->xenpmu_data->vcpu_id = sampled->vcpu_id;
         vpmu->xenpmu_data->pcpu_id = smp_processor_id();
 
@@ -606,7 +615,8 @@ long do_xenpmu_op(int op, 
XEN_GUEST_HANDLE_PARAM(xen_pmu_params_t) arg)
         if ( copy_from_guest(&pmu_params, arg, 1) )
             return -EFAULT;
 
-        if ( pmu_params.val & ~(XENPMU_MODE_SELF | XENPMU_MODE_HV) )
+        if ( pmu_params.val & ~(XENPMU_MODE_SELF | XENPMU_MODE_HV |
+                                XENPMU_MODE_ALL) )
             return -EINVAL;
 
         /*
@@ -620,7 +630,7 @@ long do_xenpmu_op(int op, 
XEN_GUEST_HANDLE_PARAM(xen_pmu_params_t) arg)
         current_mode = vpmu_mode;
         vpmu_mode = pmu_params.val;
 
-        if ( vpmu_mode == XENPMU_MODE_OFF )
+        if ( (vpmu_mode == XENPMU_MODE_OFF) || (vpmu_mode == XENPMU_MODE_ALL) )
         {
             /*
              * Make sure all (non-dom0) VCPUs have unloaded their VPMUs. This
diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c
index bc0c9c3..4e02359 100644
--- a/xen/arch/x86/traps.c
+++ b/xen/arch/x86/traps.c
@@ -2578,6 +2578,10 @@ static int emulate_privileged_op(struct cpu_user_regs 
*regs)
         case MSR_AMD_FAM15H_EVNTSEL0...MSR_AMD_FAM15H_PERFCTR5:
                 if ( vpmu_msr || (boot_cpu_data.x86_vendor == X86_VENDOR_AMD) )
                 {
+                    if ( (vpmu_mode & XENPMU_MODE_ALL) &&
+                         !is_hardware_domain(v->domain) )
+                        break;
+
                     if ( vpmu_do_wrmsr(regs->ecx, msr_content, 0) )
                         goto fail;
                 }
@@ -2700,6 +2704,14 @@ static int emulate_privileged_op(struct cpu_user_regs 
*regs)
         case MSR_AMD_FAM15H_EVNTSEL0...MSR_AMD_FAM15H_PERFCTR5:
                 if ( vpmu_msr || (boot_cpu_data.x86_vendor == X86_VENDOR_AMD) )
                 {
+                    if ( (vpmu_mode & XENPMU_MODE_ALL) &&
+                         !is_hardware_domain(v->domain) )
+                    {
+                        /* Don't leak PMU MSRs to unprivileged domains */
+                        regs->eax = regs->edx = 0;
+                        break;
+                    }
+
                     if ( vpmu_do_rdmsr(regs->ecx, &msr_content) )
                         goto fail;
 
diff --git a/xen/include/public/pmu.h b/xen/include/public/pmu.h
index a1886a5..f900f90 100644
--- a/xen/include/public/pmu.h
+++ b/xen/include/public/pmu.h
@@ -51,10 +51,13 @@ DEFINE_XEN_GUEST_HANDLE(xen_pmu_params_t);
  * - XENPMU_MODE_SELF:  Guests can profile themselves
  * - XENPMU_MODE_HV:    Guests can profile themselves, dom0 profiles
  *                      itself and Xen
+ * - XENPMU_MODE_ALL:   Only dom0 has access to VPMU and it profiles
+ *                      everyone: itself, the hypervisor and the guests.
  */
 #define XENPMU_MODE_OFF           0
 #define XENPMU_MODE_SELF          (1<<0)
 #define XENPMU_MODE_HV            (1<<1)
+#define XENPMU_MODE_ALL           (1<<2)
 
 /*
  * PMU features:
-- 
1.8.1.4


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