xen: Expose the PMU to the guests

Add parameter vpmu to xl domain configuration syntax
to enable the access to PMU registers by disabling
the PMU traps(currently only for ARM).

The current status is that the PMU registers are not
virtualized and the physical registers are directly
accessible when this parameter is enabled. There is no
interrupt support and Xen will not save/restore the
register values on context switches.

According to Arm Arm, section D7.1:
"The Performance Monitors Extension is common
to AArch64 operation and AArch32 operation."
That means we have an ensurance that if PMU is
present in one exception state, it must also be
present in the other.

Please note that this feature is experimental.

Signed-off-by: Michal Orzel <michal.orzel@arm.com>
Signed-off-by: Julien Grall <julien@xen.org>
Reviewed-by: Bertrand Marquis <bertrand.marquis@arm.com>
Acked-by: Anthony PERARD <anthony.perard@citrix.com>
Acked-by: Ian Jackson <iwj@xenproject.org>

diff --git a/SUPPORT.md b/SUPPORT.md
index 317392d8f3d193a3cdf2d13d0673cdc7ec69df73..3a34933c89a815259c736220976004ab710dabf6 100644 (file)
--- a/SUPPORT.md
+++ b/SUPPORT.md
@@ -671,11 +671,19 @@ such as KVM, Hyper-V, Bromium, and so on as guests.
 
 ### vPMU
 
-Virtual Performance Management Unit for HVM guests
+Virtual Performance Management Unit
 
-    Status, x86: Supported, Not security supported
+    Status, x86 HVM: Supported, Not security supported
+    Status, ARM: Experimental
+
+On ARM, support for accessing PMU registers from the guests.
+There is no interrupt support and Xen will not save/restore
+the register values on context switches.
+
+Disabled by default.
+On ARM, enable with guest parameter.
+On x86, enable with hypervisor command line option.
 
-Disabled by default (enable with hypervisor command line option).
 This feature is not security supported: see https://xenbits.xen.org/xsa/advisory-163.html
 
 ### Argo: Inter-domain message delivery by hypercall

diff --git a/docs/man/xl.cfg.5.pod.in b/docs/man/xl.cfg.5.pod.in
index 4b1e3028d233fc374dc2b5c5b60a4827caa79337..55c48812051c56288dfa3c20d01745a04fd8b577 100644 (file)
--- a/docs/man/xl.cfg.5.pod.in
+++ b/docs/man/xl.cfg.5.pod.in
@@ -690,6 +690,23 @@ default.
 B<NOTE>: Acceptable values are platform specific.  For Intel Processor
 Trace, this value must be a power of 2 between 4k and 16M.
 
+=item B<vpmu=BOOLEAN>
+
+Currently ARM only.
+
+Specifies whether to enable the access to PMU registers by disabling
+the PMU traps.
+
+The PMU registers are not virtualized and the physical registers are directly
+accessible when this parameter is enabled. There is no interrupt support and
+Xen will not save/restore the register values on context switches.
+
+vPMU, by design and purpose, exposes system level performance
+information to the guest. Only to be used by sufficiently privileged
+domains. This feature is currently in experimental state.
+
+If this option is not specified then it will default to B<false>.
+
 =back
 
 =head2 Devices

diff --git a/tools/golang/xenlight/helpers.gen.go b/tools/golang/xenlight/helpers.gen.go
index c8669837d8068e6ba1b954ebc45015df3b5558cf..2449580badb6dcfcbf5b03a6f351ba01c276daf9 100644 (file)
--- a/tools/golang/xenlight/helpers.gen.go
+++ b/tools/golang/xenlight/helpers.gen.go
@@ -1119,6 +1119,9 @@ return fmt.Errorf("converting field ArchX86.MsrRelaxed: %v", err)
 }
 x.Altp2M = Altp2MMode(xc.altp2m)
 x.VmtraceBufKb = int(xc.vmtrace_buf_kb)
+if err := x.Vpmu.fromC(&xc.vpmu);err != nil {
+return fmt.Errorf("converting field Vpmu: %v", err)
+}
 
  return nil}
 
@@ -1600,6 +1603,9 @@ return fmt.Errorf("converting field ArchX86.MsrRelaxed: %v", err)
 }
 xc.altp2m = C.libxl_altp2m_mode(x.Altp2M)
 xc.vmtrace_buf_kb = C.int(x.VmtraceBufKb)
+if err := x.Vpmu.toC(&xc.vpmu); err != nil {
+return fmt.Errorf("converting field Vpmu: %v", err)
+}
 
  return nil
  }

diff --git a/tools/golang/xenlight/types.gen.go b/tools/golang/xenlight/types.gen.go
index 45f2cba3d27df070be57061688c1e7da8b9ebedc..b2e8bd1a855e08a06f8f59f059f8291facbe7d3e 100644 (file)
--- a/tools/golang/xenlight/types.gen.go
+++ b/tools/golang/xenlight/types.gen.go
@@ -521,6 +521,7 @@ MsrRelaxed Defbool
 }
 Altp2M Altp2MMode
 VmtraceBufKb int
+Vpmu Defbool
 }
 
 type DomainBuildInfoTypeUnion interface {

diff --git a/tools/include/libxl.h b/tools/include/libxl.h
index ec5e3badaec6e6553982edd48abaa7a90ba13293..ee73eb06f13302e372afcec09e7cbc43535a34e0 100644 (file)
--- a/tools/include/libxl.h
+++ b/tools/include/libxl.h
@@ -508,6 +508,12 @@
  */
 #define LIBXL_HAVE_PHYSINFO_CAP_VPMU 1
 
+/*
+ * LIBXL_HAVE_VPMU indicates that libxl_domain_build_info has a vpmu parameter,
+ * which allows to enable the access to PMU registers.
+ */
+#define LIBXL_HAVE_VPMU 1
+
 /*
  * libxl ABI compatibility
  *

diff --git a/tools/libs/light/libxl_create.c b/tools/libs/light/libxl_create.c
index e356b2106d44b5a496a7238691eadbb0e8597b53..6ebb2bfc768d060fb898619be907fc973375cce5 100644 (file)
--- a/tools/libs/light/libxl_create.c
+++ b/tools/libs/light/libxl_create.c
@@ -91,6 +91,7 @@ int libxl__domain_build_info_setdefault(libxl__gc *gc,
     }
 
     libxl_defbool_setdefault(&b_info->device_model_stubdomain, false);
+    libxl_defbool_setdefault(&b_info->vpmu, false);
 
     if (libxl_defbool_val(b_info->device_model_stubdomain) &&
         !b_info->device_model_ssidref)
@@ -622,6 +623,9 @@ int libxl__domain_make(libxl__gc *gc, libxl_domain_config *d_config,
                 create.flags |= XEN_DOMCTL_CDF_nested_virt;
         }
 
+        if (libxl_defbool_val(b_info->vpmu))
+            create.flags |= XEN_DOMCTL_CDF_vpmu;
+
         assert(info->passthrough != LIBXL_PASSTHROUGH_DEFAULT);
         LOG(DETAIL, "passthrough: %s",
             libxl_passthrough_to_string(info->passthrough));
@@ -1199,6 +1203,12 @@ int libxl__domain_config_setdefault(libxl__gc *gc,
         goto error_out;
     }
 
+    if (libxl_defbool_val(d_config->b_info.vpmu) && !physinfo.cap_vpmu) {
+        ret = ERROR_INVAL;
+        LOGD(ERROR, domid, "vPMU not supported on this platform");
+        goto error_out;
+    }
+
     ret = 0;
  error_out:
     return ret;

diff --git a/tools/libs/light/libxl_types.idl b/tools/libs/light/libxl_types.idl
index 993e83acca8a39737991eec95f11382eb4578068..b96fb5c47e7425bdf341dce595f4ad85aa9e55d2 100644 (file)
--- a/tools/libs/light/libxl_types.idl
+++ b/tools/libs/light/libxl_types.idl
@@ -655,6 +655,8 @@ libxl_domain_build_info = Struct("domain_build_info",[
     # Use zero value to disable this feature.
     ("vmtrace_buf_kb", integer),
 
+    ("vpmu", libxl_defbool),
+
     ], dir=DIR_IN,
        copy_deprecated_fn="libxl__domain_build_info_copy_deprecated",
 )

diff --git a/tools/ocaml/libs/xc/xenctrl.ml b/tools/ocaml/libs/xc/xenctrl.ml
index 7a4030a19296ccf447b92b6eee05d95c17dc40c5..86758babb383f6eec0f5c7b99248d0ad0dc2da10 100644 (file)
--- a/tools/ocaml/libs/xc/xenctrl.ml
+++ b/tools/ocaml/libs/xc/xenctrl.ml
@@ -70,6 +70,7 @@ type domain_create_flag =
        | CDF_IOMMU
        | CDF_NESTED_VIRT
        | CDF_VPCI
+       | CDF_VPMU
 
 type domain_create_iommu_opts =
        | IOMMU_NO_SHAREPT

diff --git a/tools/ocaml/libs/xc/xenctrl.mli b/tools/ocaml/libs/xc/xenctrl.mli
index 6900513e7f56f596689b37b4c95424f601fdbf38..0fdb0cc169f98682439efb3124969d5d4b8adc32 100644 (file)
--- a/tools/ocaml/libs/xc/xenctrl.mli
+++ b/tools/ocaml/libs/xc/xenctrl.mli
@@ -63,6 +63,7 @@ type domain_create_flag =
   | CDF_IOMMU
   | CDF_NESTED_VIRT
   | CDF_VPCI
+  | CDF_VPMU
 
 type domain_create_iommu_opts =
   | IOMMU_NO_SHAREPT

diff --git a/tools/xl/xl_parse.c b/tools/xl/xl_parse.c
index 17dddb4cd534956f20e9395be91dd2f9c788949c..c503b9be004e1264c7608f23695252a5032c068f 100644 (file)
--- a/tools/xl/xl_parse.c
+++ b/tools/xl/xl_parse.c
@@ -2750,6 +2750,8 @@ skip_usbdev:
                     "If it fixes an issue you are having please report to "
                     "xen-devel@lists.xenproject.org.\n");
 
+    xlu_cfg_get_defbool(config, "vpmu", &b_info->vpmu, 0);
+
     xlu_cfg_destroy(config);
 }
 

diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c
index aae44724791d45b8f5857879bd9c3a2eaf1850de..ad21c9b95028b91a056f5ea9cb206fa586904bda 100644 (file)
--- a/xen/arch/arm/domain.c
+++ b/xen/arch/arm/domain.c
@@ -276,6 +276,8 @@ static void ctxt_switch_to(struct vcpu *n)
      * timer. The interrupt needs to be injected into the guest. */
     WRITE_SYSREG(n->arch.cntkctl, CNTKCTL_EL1);
     virt_timer_restore(n);
+
+    WRITE_SYSREG(n->arch.mdcr_el2, MDCR_EL2);
 }
 
 /* Update per-VCPU guest runstate shared memory area (if registered). */
@@ -586,6 +588,10 @@ int arch_vcpu_create(struct vcpu *v)
 
     v->arch.hcr_el2 = get_default_hcr_flags();
 
+    v->arch.mdcr_el2 = HDCR_TDRA | HDCR_TDOSA | HDCR_TDA;
+    if ( !(v->domain->options & XEN_DOMCTL_CDF_vpmu) )
+        v->arch.mdcr_el2 |= HDCR_TPM | HDCR_TPMCR;
+
     if ( (rc = vcpu_vgic_init(v)) != 0 )
         goto fail;
 
@@ -621,10 +627,11 @@ void vcpu_switch_to_aarch64_mode(struct vcpu *v)
 int arch_sanitise_domain_config(struct xen_domctl_createdomain *config)
 {
     unsigned int max_vcpus;
+    unsigned int flags_required = (XEN_DOMCTL_CDF_hvm | XEN_DOMCTL_CDF_hap);
+    unsigned int flags_optional = (XEN_DOMCTL_CDF_iommu | XEN_DOMCTL_CDF_vpci |
+                                   XEN_DOMCTL_CDF_vpmu);
 
-    /* HVM and HAP must be set. IOMMU and VPCI may or may not be */
-    if ( (config->flags & ~XEN_DOMCTL_CDF_iommu & ~XEN_DOMCTL_CDF_vpci) !=
-         (XEN_DOMCTL_CDF_hvm | XEN_DOMCTL_CDF_hap) )
+    if ( (config->flags & ~flags_optional) != flags_required )
     {
         dprintk(XENLOG_INFO, "Unsupported configuration %#x\n",
                 config->flags);

diff --git a/xen/arch/arm/setup.c b/xen/arch/arm/setup.c
index 49dc90d198a7260395a6d22858ed8b8691ff429c..d5d0792ed48a9923b3a1d6ef0d6440b2e84f9993 100644 (file)
--- a/xen/arch/arm/setup.c
+++ b/xen/arch/arm/setup.c
@@ -999,6 +999,9 @@ void __init start_xen(unsigned long boot_phys_offset,
     printk("Brought up %ld CPUs\n", (long)num_online_cpus());
     /* TODO: smp_cpus_done(); */
 
+    /* This should be done in a vpmu driver but we do not have one yet. */
+    vpmu_is_available = cpu_has_pmu;
+
     /*
      * The IOMMU subsystem must be initialized before P2M as we need
      * to gather requirements regarding the maximum IPA bits supported by

diff --git a/xen/common/domain.c b/xen/common/domain.c
index 262b6c0c3cb12bc39ce3aa0f009fe97facc8d9c3..8543fb54fd513471df610c656f04cd412156c3de 100644 (file)
--- a/xen/common/domain.c
+++ b/xen/common/domain.c
@@ -480,12 +480,14 @@ static int sanitise_domain_config(struct xen_domctl_createdomain *config)
     bool hvm = config->flags & XEN_DOMCTL_CDF_hvm;
     bool hap = config->flags & XEN_DOMCTL_CDF_hap;
     bool iommu = config->flags & XEN_DOMCTL_CDF_iommu;
+    bool vpmu = config->flags & XEN_DOMCTL_CDF_vpmu;
 
     if ( config->flags &
          ~(XEN_DOMCTL_CDF_hvm | XEN_DOMCTL_CDF_hap |
            XEN_DOMCTL_CDF_s3_integrity | XEN_DOMCTL_CDF_oos_off |
            XEN_DOMCTL_CDF_xs_domain | XEN_DOMCTL_CDF_iommu |
-           XEN_DOMCTL_CDF_nested_virt | XEN_DOMCTL_CDF_vpci) )
+           XEN_DOMCTL_CDF_nested_virt | XEN_DOMCTL_CDF_vpci |
+           XEN_DOMCTL_CDF_vpmu) )
     {
         dprintk(XENLOG_INFO, "Unknown CDF flags %#x\n", config->flags);
         return -EINVAL;
@@ -534,6 +536,12 @@ static int sanitise_domain_config(struct xen_domctl_createdomain *config)
         return -EINVAL;
     }
 
+    if ( vpmu && !vpmu_is_available )
+    {
+        dprintk(XENLOG_INFO, "vpmu requested but cannot be enabled this way\n");
+        return -EINVAL;
+    }
+
     return arch_sanitise_domain_config(config);
 }
 

diff --git a/xen/include/asm-arm/domain.h b/xen/include/asm-arm/domain.h
index c9277b5c6d948991845bc4ec245502e21ce53aee..14e575288f77a4a285d9c53d360427c453e4f784 100644 (file)
--- a/xen/include/asm-arm/domain.h
+++ b/xen/include/asm-arm/domain.h
@@ -166,6 +166,7 @@ struct arch_vcpu
 
     /* HYP configuration */
     register_t hcr_el2;
+    register_t mdcr_el2;
 
     uint32_t teecr, teehbr; /* ThumbEE, 32-bit guests only */
 #ifdef CONFIG_ARM_32

diff --git a/xen/include/public/domctl.h b/xen/include/public/domctl.h
index 4cb3f662c28ccd30a49701241e910df6ef5cea17..a53cbd16f4756c22aa0b2c35860dbfa718144845 100644 (file)
--- a/xen/include/public/domctl.h
+++ b/xen/include/public/domctl.h
@@ -71,9 +71,11 @@ struct xen_domctl_createdomain {
 #define _XEN_DOMCTL_CDF_nested_virt   6
 #define XEN_DOMCTL_CDF_nested_virt    (1U << _XEN_DOMCTL_CDF_nested_virt)
 #define XEN_DOMCTL_CDF_vpci           (1U << 7)
+/* Should we expose the vPMU to the guest? */
+#define XEN_DOMCTL_CDF_vpmu           (1U << 8)
 
 /* Max XEN_DOMCTL_CDF_* constant.  Used for ABI checking. */
-#define XEN_DOMCTL_CDF_MAX XEN_DOMCTL_CDF_vpci
+#define XEN_DOMCTL_CDF_MAX XEN_DOMCTL_CDF_vpmu
 
     uint32_t flags;