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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [PATCH v7 06/10] xen/domctl: Add XEN_DOMCTL_vmtrace_op
From: Michał Leszczyński <michal.leszczynski@xxxxxxx>
Implement an interface to configure and control tracing operations. Reuse the
existing SETDEBUGGING flask vector rather than inventing a new one.
Userspace using this interface is going to need platform specific knowledge
anyway to interpret the contents of the trace buffer. While some operations
(e.g. enable/disable) can reasonably be generic, others cannot. Provide an
explicitly-platform specific pair of get/set operations to reduce API churn as
new options get added/enabled.
For the VMX specific Processor Trace implementation, tolerate reading and
modifying a safe subset of bits in CTL, STATUS and OUTPUT_MASK. This permits
userspace to control the content which gets logged, but prevents modification
of details such as the position/size of the output buffer.
Signed-off-by: Michał Leszczyński <michal.leszczynski@xxxxxxx>
Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
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:
* Major chop&change within the series.
---
xen/arch/x86/domctl.c | 55 +++++++++++++++
xen/arch/x86/hvm/vmx/vmx.c | 151 ++++++++++++++++++++++++++++++++++++++++++
xen/include/asm-x86/hvm/hvm.h | 63 ++++++++++++++++++
xen/include/public/domctl.h | 35 ++++++++++
xen/xsm/flask/hooks.c | 1 +
5 files changed, 305 insertions(+)
diff --git a/xen/arch/x86/domctl.c b/xen/arch/x86/domctl.c
index b28cfe9817..aa6dfe8eed 100644
--- a/xen/arch/x86/domctl.c
+++ b/xen/arch/x86/domctl.c
@@ -155,6 +155,55 @@ void arch_get_domain_info(const struct domain *d,
info->arch_config.emulation_flags = d->arch.emulation_flags;
}
+static int do_vmtrace_op(struct domain *d, struct xen_domctl_vmtrace_op *op,
+ XEN_GUEST_HANDLE_PARAM(xen_domctl_t) u_domctl)
+{
+ struct vcpu *v;
+ int rc;
+
+ if ( !d->vmtrace_frames || d == current->domain /* No vcpu_pause() */ )
+ return -EINVAL;
+
+ ASSERT(is_hvm_domain(d)); /* Restricted by domain creation logic. */
+
+ v = domain_vcpu(d, op->vcpu);
+ if ( !v )
+ return -ENOENT;
+
+ vcpu_pause(v);
+ switch ( op->cmd )
+ {
+ case XEN_DOMCTL_vmtrace_enable:
+ case XEN_DOMCTL_vmtrace_disable:
+ case XEN_DOMCTL_vmtrace_reset_and_enable:
+ rc = hvm_vmtrace_control(
+ v, op->cmd != XEN_DOMCTL_vmtrace_disable,
+ op->cmd == XEN_DOMCTL_vmtrace_reset_and_enable);
+ break;
+
+ case XEN_DOMCTL_vmtrace_output_position:
+ rc = hvm_vmtrace_output_position(v, &op->value);
+ if ( rc >= 0 )
+ rc = 0;
+ break;
+
+ case XEN_DOMCTL_vmtrace_get_option:
+ rc = hvm_vmtrace_get_option(v, op->key, &op->value);
+ break;
+
+ case XEN_DOMCTL_vmtrace_set_option:
+ rc = hvm_vmtrace_set_option(v, op->key, op->value);
+ break;
+
+ default:
+ rc = -EOPNOTSUPP;
+ break;
+ }
+ vcpu_unpause(v);
+
+ return rc;
+}
+
#define MAX_IOPORTS 0x10000
long arch_do_domctl(
@@ -1320,6 +1369,12 @@ long arch_do_domctl(
domain_unpause(d);
break;
+ case XEN_DOMCTL_vmtrace_op:
+ ret = do_vmtrace_op(d, &domctl->u.vmtrace_op, u_domctl);
+ if ( !ret )
+ copyback = true;
+ break;
+
default:
ret = iommu_do_domctl(domctl, d, u_domctl);
break;
diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
index 93121fbf27..d4e7b50b8a 100644
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -2261,6 +2261,153 @@ static bool vmx_get_pending_event(struct vcpu *v,
struct x86_event *info)
return true;
}
+static int vmtrace_get_option(struct vcpu *v, uint64_t key, uint64_t *output)
+{
+ const struct vcpu_msrs *msrs = v->arch.msrs;
+
+ /*
+ * We only let vmtrace agents see and modify a subset of bits in
+ * MSR_RTIT_CTL. These all pertain to date emitted into the trace
+ * buffer(s). Must not include controls pertaining to the
+ * structure/position of the trace buffer(s).
+ */
+#define RTIT_CTL_MASK \
+ (RTIT_CTL_TRACE_EN | RTIT_CTL_OS | RTIT_CTL_USR | RTIT_CTL_TSC_EN | \
+ RTIT_CTL_DIS_RETC | RTIT_CTL_BRANCH_EN)
+
+ /*
+ * Status bits restricted to the first-gen subset (i.e. no further CPUID
+ * requirements.)
+ */
+#define RTIT_STATUS_MASK \
+ (RTIT_STATUS_FILTER_EN | RTIT_STATUS_CONTEXT_EN | RTIT_STATUS_TRIGGER_EN |
\
+ RTIT_STATUS_ERROR | RTIT_STATUS_STOPPED)
+
+ switch ( key )
+ {
+ case MSR_RTIT_OUTPUT_MASK:
+ *output = msrs->rtit.output_mask;
+ break;
+
+ case MSR_RTIT_CTL:
+ *output = msrs->rtit.ctl & RTIT_CTL_MASK;
+ break;
+
+ case MSR_RTIT_STATUS:
+ *output = msrs->rtit.status & RTIT_STATUS_MASK;
+ break;
+
+ default:
+ *output = 0;
+ return -EINVAL;
+ }
+ return 0;
+}
+
+static int vmtrace_set_option(struct vcpu *v, uint64_t key, uint64_t value)
+{
+ struct vcpu_msrs *msrs = v->arch.msrs;
+ bool new_en, old_en = msrs->rtit.ctl & RTIT_CTL_TRACE_EN;
+
+ switch ( key )
+ {
+ case MSR_RTIT_OUTPUT_MASK:
+ /*
+ * MSR_RTIT_OUTPUT_MASK, when using Single Output mode, has a limit
+ * field in the lower 32 bits, and an offset in the upper 32 bits.
+ *
+ * Limit is fixed by the vmtrace buffer size and must not be
+ * controlled by userspace, while offset must be within the limit.
+ *
+ * Drop writes to the limit field to simply userspace wanting to reset
+ * the offset by writing 0.
+ */
+ if ( (value >> 32) > msrs->rtit.output_limit )
+ return -EINVAL;
+ msrs->rtit.output_offset = value >> 32;
+ break;
+
+ case MSR_RTIT_CTL:
+ if ( value & ~RTIT_CTL_MASK )
+ return -EINVAL;
+
+ msrs->rtit.ctl &= ~RTIT_CTL_MASK;
+ msrs->rtit.ctl |= (value & RTIT_CTL_MASK);
+ break;
+
+ case MSR_RTIT_STATUS:
+ if ( value & ~RTIT_STATUS_MASK )
+ return -EINVAL;
+
+ msrs->rtit.status &= ~RTIT_STATUS_MASK;
+ msrs->rtit.status |= (value & RTIT_STATUS_MASK);
+ break;
+
+ default:
+ return -EINVAL;
+ }
+
+ new_en = msrs->rtit.ctl & RTIT_CTL_TRACE_EN;
+
+ /* ctl.trace_en changed => update MSR load/save lists appropriately. */
+ if ( !old_en && new_en )
+ {
+ if ( vmx_add_guest_msr(v, MSR_RTIT_CTL, msrs->rtit.ctl) ||
+ vmx_add_host_load_msr(v, MSR_RTIT_CTL, 0) )
+ {
+ /*
+ * The only failure cases here are failing the
+ * singleton-per-domain memory allocation, or exceeding the space
+ * in the allocation. We could unwind in principle, but there is
+ * nothing userspace can usefully do to continue using this VM.
+ */
+ domain_crash(v->domain);
+ return -ENXIO;
+ }
+ }
+ else if ( old_en && !new_en )
+ {
+ vmx_del_msr(v, MSR_RTIT_CTL, VMX_MSR_GUEST);
+ vmx_del_msr(v, MSR_RTIT_CTL, VMX_MSR_HOST);
+ }
+
+ return 0;
+}
+
+static int vmtrace_control(struct vcpu *v, bool enable, bool reset)
+{
+ struct vcpu_msrs *msrs = v->arch.msrs;
+ uint64_t new_ctl;
+ int rc;
+
+ if ( v->arch.hvm.vmx.ipt_active == enable )
+ return -EINVAL;
+
+ if ( reset )
+ {
+ msrs->rtit.status = 0;
+ msrs->rtit.output_offset = 0;
+ }
+
+ new_ctl = msrs->rtit.ctl & ~RTIT_CTL_TRACE_EN;
+ if ( enable )
+ new_ctl |= RTIT_CTL_TRACE_EN;
+
+ rc = vmtrace_set_option(v, MSR_RTIT_CTL, new_ctl);
+ if ( rc )
+ return rc;
+
+ v->arch.hvm.vmx.ipt_active = enable;
+
+ return 0;
+}
+
+static int vmtrace_output_position(struct vcpu *v, uint64_t *pos)
+{
+ *pos = v->arch.msrs->rtit.output_offset;
+ return v->arch.hvm.vmx.ipt_active;
+}
+
static struct hvm_function_table __initdata vmx_function_table = {
.name = "VMX",
.cpu_up_prepare = vmx_cpu_up_prepare,
@@ -2316,6 +2463,10 @@ static struct hvm_function_table __initdata
vmx_function_table = {
.altp2m_vcpu_update_vmfunc_ve = vmx_vcpu_update_vmfunc_ve,
.altp2m_vcpu_emulate_ve = vmx_vcpu_emulate_ve,
.altp2m_vcpu_emulate_vmfunc = vmx_vcpu_emulate_vmfunc,
+ .vmtrace_control = vmtrace_control,
+ .vmtrace_output_position = vmtrace_output_position,
+ .vmtrace_set_option = vmtrace_set_option,
+ .vmtrace_get_option = vmtrace_get_option,
.tsc_scaling = {
.max_ratio = VMX_TSC_MULTIPLIER_MAX,
},
diff --git a/xen/include/asm-x86/hvm/hvm.h b/xen/include/asm-x86/hvm/hvm.h
index 334bd573b9..960ec03917 100644
--- a/xen/include/asm-x86/hvm/hvm.h
+++ b/xen/include/asm-x86/hvm/hvm.h
@@ -214,6 +214,12 @@ struct hvm_function_table {
bool_t (*altp2m_vcpu_emulate_ve)(struct vcpu *v);
int (*altp2m_vcpu_emulate_vmfunc)(const struct cpu_user_regs *regs);
+ /* vmtrace */
+ int (*vmtrace_control)(struct vcpu *v, bool enable, bool reset);
+ 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);
+
/*
* Parameters and callbacks for hardware-assisted TSC scaling,
* which are valid only when the hardware feature is available.
@@ -655,6 +661,41 @@ static inline bool altp2m_vcpu_emulate_ve(struct vcpu *v)
return false;
}
+static inline int hvm_vmtrace_control(struct vcpu *v, bool enable, bool reset)
+{
+ if ( hvm_funcs.vmtrace_control )
+ return hvm_funcs.vmtrace_control(v, enable, reset);
+
+ return -EOPNOTSUPP;
+}
+
+/* Returns -errno, or a boolean of whether tracing is currently active. */
+static inline int hvm_vmtrace_output_position(struct vcpu *v, uint64_t *pos)
+{
+ if ( hvm_funcs.vmtrace_output_position )
+ return hvm_funcs.vmtrace_output_position(v, pos);
+
+ return -EOPNOTSUPP;
+}
+
+static inline int hvm_vmtrace_set_option(
+ struct vcpu *v, uint64_t key, uint64_t value)
+{
+ if ( hvm_funcs.vmtrace_set_option )
+ return hvm_funcs.vmtrace_set_option(v, key, value);
+
+ return -EOPNOTSUPP;
+}
+
+static inline int hvm_vmtrace_get_option(
+ struct vcpu *v, uint64_t key, uint64_t *value)
+{
+ if ( hvm_funcs.vmtrace_get_option )
+ return hvm_funcs.vmtrace_get_option(v, key, value);
+
+ return -EOPNOTSUPP;
+}
+
/*
* This must be defined as a macro instead of an inline function,
* because it uses 'struct vcpu' and 'struct domain' which have
@@ -751,6 +792,28 @@ static inline bool
hvm_has_set_descriptor_access_exiting(void)
return false;
}
+static inline int hvm_vmtrace_control(struct vcpu *v, bool enable, bool reset)
+{
+ return -EOPNOTSUPP;
+}
+
+static inline int hvm_vmtrace_output_position(struct vcpu *v, uint64_t *pos)
+{
+ return -EOPNOTSUPP;
+}
+
+static inline int hvm_vmtrace_set_option(
+ struct vcpu *v, uint64_t key, uint64_t value)
+{
+ return -EOPNOTSUPP;
+}
+
+static inline int hvm_vmtrace_get_option(
+ struct vcpu *v, uint64_t key, uint64_t *value)
+{
+ return -EOPNOTSUPP;
+}
+
#define is_viridian_domain(d) ((void)(d), false)
#define is_viridian_vcpu(v) ((void)(v), false)
#define has_viridian_time_ref_count(d) ((void)(d), false)
diff --git a/xen/include/public/domctl.h b/xen/include/public/domctl.h
index 1585678d50..218593e548 100644
--- a/xen/include/public/domctl.h
+++ b/xen/include/public/domctl.h
@@ -1133,6 +1133,39 @@ struct xen_domctl_vuart_op {
*/
};
+/* XEN_DOMCTL_vmtrace_op: Perform VM tracing operations. */
+struct xen_domctl_vmtrace_op {
+ uint32_t cmd; /* IN */
+ uint32_t vcpu; /* IN */
+ uint64_aligned_t key; /* IN - @cmd specific data. */
+ uint64_aligned_t value; /* IN/OUT - @cmd specific data. */
+
+ /*
+ * General enable/disable of tracing.
+ *
+ * XEN_DOMCTL_vmtrace_reset_and_enable is provided as optimisation for
+ * common usecases, which want to reset status and position information
+ * when turning tracing back on.
+ */
+#define XEN_DOMCTL_vmtrace_enable 1
+#define XEN_DOMCTL_vmtrace_disable 2
+#define XEN_DOMCTL_vmtrace_reset_and_enable 3
+
+ /* Obtain the current output position within the buffer. Fills @value. */
+#define XEN_DOMCTL_vmtrace_output_position 4
+
+ /*
+ * Get/Set platform specific configuration.
+ *
+ * For Intel Processor Trace, @key/@value are interpreted as MSR
+ * reads/writes to MSR_RTIT_*, filtered to a safe subset.
+ */
+#define XEN_DOMCTL_vmtrace_get_option 5
+#define XEN_DOMCTL_vmtrace_set_option 6
+};
+typedef struct xen_domctl_vmtrace_op xen_domctl_vmtrace_op_t;
+DEFINE_XEN_GUEST_HANDLE(xen_domctl_vmtrace_op_t);
+
struct xen_domctl {
uint32_t cmd;
#define XEN_DOMCTL_createdomain 1
@@ -1217,6 +1250,7 @@ struct xen_domctl {
#define XEN_DOMCTL_vuart_op 81
#define XEN_DOMCTL_get_cpu_policy 82
#define XEN_DOMCTL_set_cpu_policy 83
+#define XEN_DOMCTL_vmtrace_op 84
#define XEN_DOMCTL_gdbsx_guestmemio 1000
#define XEN_DOMCTL_gdbsx_pausevcpu 1001
#define XEN_DOMCTL_gdbsx_unpausevcpu 1002
@@ -1277,6 +1311,7 @@ struct xen_domctl {
struct xen_domctl_monitor_op monitor_op;
struct xen_domctl_psr_alloc psr_alloc;
struct xen_domctl_vuart_op vuart_op;
+ struct xen_domctl_vmtrace_op vmtrace_op;
uint8_t pad[128];
} u;
};
diff --git a/xen/xsm/flask/hooks.c b/xen/xsm/flask/hooks.c
index 19b0d9e3eb..3eba495ab3 100644
--- a/xen/xsm/flask/hooks.c
+++ b/xen/xsm/flask/hooks.c
@@ -703,6 +703,7 @@ static int flask_domctl(struct domain *d, int cmd)
return current_has_perm(d, SECCLASS_DOMAIN2, DOMAIN2__VM_EVENT);
case XEN_DOMCTL_debug_op:
+ case XEN_DOMCTL_vmtrace_op:
case XEN_DOMCTL_gdbsx_guestmemio:
case XEN_DOMCTL_gdbsx_pausevcpu:
case XEN_DOMCTL_gdbsx_unpausevcpu:
--
2.11.0
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