[PATCH v8 15/16] xen/vmtrace: support for VM forks

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

From: Tamas K Lengyel <tamas.lengyel@xxxxxxxxx>

Implement vmtrace_reset_pt function. Properly set IPT
state for VM forks.

Signed-off-by: Tamas K Lengyel <tamas.lengyel@xxxxxxxxx>
Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>
CC: Wei Liu <wl@xxxxxxx>
CC: Jun Nakajima <jun.nakajima@xxxxxxxxx>
CC: Kevin Tian <kevin.tian@xxxxxxxxx>
CC: Michał Leszczyński <michal.leszczynski@xxxxxxx>
CC: Tamas K Lengyel <tamas@xxxxxxxxxxxxx>

v7:
 * New
---
 xen/arch/x86/hvm/vmx/vmx.c    | 11 +++++++++++
 xen/arch/x86/mm/mem_sharing.c |  3 +++
 xen/include/asm-x86/hvm/hvm.h |  9 +++++++++
 3 files changed, 23 insertions(+)

diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
index a64c4e4177..5a33d8024e 100644
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -2412,6 +2412,16 @@ static int vmtrace_output_position(struct vcpu *v, 
uint64_t *pos)
     return v->arch.hvm.vmx.ipt_active;
 }
 
+static int vmtrace_reset(struct vcpu *v)
+{
+    if ( !v->arch.hvm.vmx.ipt_active )
+        return -EINVAL;
+
+    v->arch.msrs->rtit.output_offset = 0;
+    v->arch.msrs->rtit.status = 0;
+    return 0;
+}
+
 static struct hvm_function_table __initdata vmx_function_table = {
     .name                 = "VMX",
     .cpu_up_prepare       = vmx_cpu_up_prepare,
@@ -2471,6 +2481,7 @@ static struct hvm_function_table __initdata 
vmx_function_table = {
     .vmtrace_output_position = vmtrace_output_position,
     .vmtrace_set_option = vmtrace_set_option,
     .vmtrace_get_option = vmtrace_get_option,
+    .vmtrace_reset = vmtrace_reset,
     .tsc_scaling = {
         .max_ratio = VMX_TSC_MULTIPLIER_MAX,
     },
diff --git a/xen/arch/x86/mm/mem_sharing.c b/xen/arch/x86/mm/mem_sharing.c
index adaeab4612..00ada05c10 100644
--- a/xen/arch/x86/mm/mem_sharing.c
+++ b/xen/arch/x86/mm/mem_sharing.c
@@ -1632,6 +1632,8 @@ static int copy_vcpu_settings(struct domain *cd, const 
struct domain *d)
             copy_domain_page(new_vcpu_info_mfn, vcpu_info_mfn);
         }
 
+        hvm_vmtrace_reset(cd_vcpu);
+
         /*
          * TODO: to support VMs with PV interfaces copy additional
          * settings here, such as PV timers.
@@ -1782,6 +1784,7 @@ static int fork(struct domain *cd, struct domain *d)
         cd->max_pages = d->max_pages;
         *cd->arch.cpuid = *d->arch.cpuid;
         *cd->arch.msr = *d->arch.msr;
+        cd->vmtrace_size = d->vmtrace_size;
         cd->parent = d;
     }
 
diff --git a/xen/include/asm-x86/hvm/hvm.h b/xen/include/asm-x86/hvm/hvm.h
index 960ec03917..150746de66 100644
--- a/xen/include/asm-x86/hvm/hvm.h
+++ b/xen/include/asm-x86/hvm/hvm.h
@@ -219,6 +219,7 @@ struct hvm_function_table {
     int (*vmtrace_output_position)(struct vcpu *v, uint64_t *pos);
     int (*vmtrace_set_option)(struct vcpu *v, uint64_t key, uint64_t value);
     int (*vmtrace_get_option)(struct vcpu *v, uint64_t key, uint64_t *value);
+    int (*vmtrace_reset)(struct vcpu *v);
 
     /*
      * Parameters and callbacks for hardware-assisted TSC scaling,
@@ -696,6 +697,14 @@ static inline int hvm_vmtrace_get_option(
     return -EOPNOTSUPP;
 }
 
+static inline int hvm_vmtrace_reset(struct vcpu *v)
+{
+    if ( hvm_funcs.vmtrace_reset )
+        return hvm_funcs.vmtrace_reset(v);
+
+    return -EOPNOTSUPP;
+}
+
 /*
  * This must be defined as a macro instead of an inline function,
  * because it uses 'struct vcpu' and 'struct domain' which have
-- 
2.11.0