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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [xen master] xen: make VMTRACE support optional
commit 4202f7d0cd01370d0070f78aef1e47cbb3fcce39
Author: Grygorii Strashko <grygorii_strashko@xxxxxxxx>
AuthorDate: Thu Feb 5 10:26:45 2026 +0100
Commit: Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Thu Feb 5 10:26:45 2026 +0100
xen: make VMTRACE support optional
The VMTRACE feature is depends on Platform/Arch HW and code support and now
can be used only on x86 HVM with Intel VT-x (INTEL_VMX) enabled.
This makes VMTRACE support optional by introducing HVM Kconfig option:
- CONFIG_VMTRACE to enable/disable the feature.
Signed-off-by: Grygorii Strashko <grygorii_strashko@xxxxxxxx>
Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
Acked-by: Tamas K Lengyel <tamas@xxxxxxxxxxxxx>
---
xen/arch/x86/domctl.c | 4 ++++
xen/arch/x86/hvm/Kconfig | 12 ++++++++++++
xen/arch/x86/hvm/vmx/vmcs.c | 2 ++
xen/arch/x86/hvm/vmx/vmx.c | 11 +++++++++++
xen/arch/x86/include/asm/guest-msr.h | 2 ++
xen/arch/x86/include/asm/hvm/hvm.h | 34 ++++++++++++---------------------
xen/arch/x86/include/asm/hvm/vmx/vmcs.h | 2 ++
xen/arch/x86/mm/mem_sharing.c | 2 ++
xen/arch/x86/vm_event.c | 8 +++++---
xen/common/domain.c | 10 ++++++++++
xen/common/memory.c | 6 ++++++
xen/common/vm_event.c | 3 ++-
xen/include/xen/domain.h | 4 ++++
xen/include/xen/sched.h | 4 ++++
14 files changed, 78 insertions(+), 26 deletions(-)
diff --git a/xen/arch/x86/domctl.c b/xen/arch/x86/domctl.c
index 6153e3c07e..d9521808dc 100644
--- a/xen/arch/x86/domctl.c
+++ b/xen/arch/x86/domctl.c
@@ -154,6 +154,7 @@ void arch_get_domain_info(const struct domain *d,
static int do_vmtrace_op(struct domain *d, struct xen_domctl_vmtrace_op *op,
XEN_GUEST_HANDLE_PARAM(xen_domctl_t) u_domctl)
{
+#ifdef CONFIG_VMTRACE
struct vcpu *v;
int rc;
@@ -198,6 +199,9 @@ static int do_vmtrace_op(struct domain *d, struct
xen_domctl_vmtrace_op *op,
vcpu_unpause(v);
return rc;
+#else
+ return -EOPNOTSUPP;
+#endif
}
#define MAX_IOPORTS 0x10000
diff --git a/xen/arch/x86/hvm/Kconfig b/xen/arch/x86/hvm/Kconfig
index 25eb3e374f..f32bf5cbb7 100644
--- a/xen/arch/x86/hvm/Kconfig
+++ b/xen/arch/x86/hvm/Kconfig
@@ -34,6 +34,18 @@ config INTEL_VMX
If your system includes a processor with Intel VT-x support, say Y.
If in doubt, say Y.
+config VMTRACE
+ bool "HW VM tracing support"
+ depends on INTEL_VMX
+ default y
+ help
+ Enables HW VM tracing support which allows to configure HW processor
+ features (vmtrace_op) to enable capturing information about software
+ execution using dedicated hardware facilities with minimal
interference
+ to the software being traced. The trace data can be retrieved using
buffer
+ shared between Xen and domain
+ (see XENMEM_acquire_resource(XENMEM_resource_vmtrace_buf)).
+
config HVM_FEP
bool "HVM Forced Emulation Prefix support (UNSUPPORTED)" if UNSUPPORTED
default DEBUG
diff --git a/xen/arch/x86/hvm/vmx/vmcs.c b/xen/arch/x86/hvm/vmx/vmcs.c
index d610988bf9..c2e7f9aed3 100644
--- a/xen/arch/x86/hvm/vmx/vmcs.c
+++ b/xen/arch/x86/hvm/vmx/vmcs.c
@@ -306,6 +306,7 @@ static int vmx_init_vmcs_config(bool bsp)
rdmsrl(MSR_IA32_VMX_MISC, _vmx_misc_cap);
+#ifdef CONFIG_VMTRACE
/* Check whether IPT is supported in VMX operation. */
if ( bsp )
vmtrace_available = cpu_has_proc_trace &&
@@ -317,6 +318,7 @@ static int vmx_init_vmcs_config(bool bsp)
smp_processor_id());
return -EINVAL;
}
+#endif
if ( caps.cpu_based_exec_control & CPU_BASED_ACTIVATE_SECONDARY_CONTROLS )
{
diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
index 40e4c71244..82c55f49ae 100644
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -622,6 +622,7 @@ static void cf_check domain_creation_finished(struct domain
*d)
static void vmx_init_ipt(struct vcpu *v)
{
+#ifdef CONFIG_VMTRACE
unsigned int size = v->domain->vmtrace_size;
if ( !size )
@@ -632,6 +633,7 @@ static void vmx_init_ipt(struct vcpu *v)
ASSERT(size >= PAGE_SIZE && (size & (size - 1)) == 0);
v->arch.msrs->rtit.output_limit = size - 1;
+#endif
}
static int cf_check vmx_vcpu_initialise(struct vcpu *v)
@@ -723,11 +725,13 @@ static void vmx_save_guest_msrs(struct vcpu *v)
*/
v->arch.hvm.vmx.shadow_gs = read_gs_shadow();
+#ifdef CONFIG_VMTRACE
if ( v->arch.hvm.vmx.ipt_active )
{
rdmsrl(MSR_RTIT_OUTPUT_MASK, msrs->rtit.output_mask);
rdmsrl(MSR_RTIT_STATUS, msrs->rtit.status);
}
+#endif
if ( cp->feat.pks )
msrs->pkrs = rdpkrs_and_cache();
@@ -746,12 +750,14 @@ static void vmx_restore_guest_msrs(struct vcpu *v)
if ( cpu_has_msr_tsc_aux )
wrmsr_tsc_aux(msrs->tsc_aux);
+#ifdef CONFIG_VMTRACE
if ( v->arch.hvm.vmx.ipt_active )
{
wrmsrl(MSR_RTIT_OUTPUT_BASE, page_to_maddr(v->vmtrace.pg));
wrmsrl(MSR_RTIT_OUTPUT_MASK, msrs->rtit.output_mask);
wrmsrl(MSR_RTIT_STATUS, msrs->rtit.status);
}
+#endif
if ( cp->feat.pks )
wrpkrs(msrs->pkrs);
@@ -2629,6 +2635,7 @@ static bool cf_check vmx_get_pending_event(
return true;
}
+#ifdef CONFIG_VMTRACE
/*
* We only let vmtrace agents see and modify a subset of bits in MSR_RTIT_CTL.
* These all pertain to data-emitted into the trace buffer(s). Must not
@@ -2771,6 +2778,7 @@ static int cf_check vmtrace_reset(struct vcpu *v)
v->arch.msrs->rtit.status = 0;
return 0;
}
+#endif
static uint64_t cf_check vmx_get_reg(struct vcpu *v, unsigned int reg)
{
@@ -2945,11 +2953,14 @@ static struct hvm_function_table __initdata_cf_clobber
vmx_function_table = {
.altp2m_vcpu_emulate_ve = vmx_vcpu_emulate_ve,
.altp2m_vcpu_emulate_vmfunc = vmx_vcpu_emulate_vmfunc,
#endif
+
+#ifdef CONFIG_VMTRACE
.vmtrace_control = vmtrace_control,
.vmtrace_output_position = vmtrace_output_position,
.vmtrace_set_option = vmtrace_set_option,
.vmtrace_get_option = vmtrace_get_option,
.vmtrace_reset = vmtrace_reset,
+#endif
.get_reg = vmx_get_reg,
.set_reg = vmx_set_reg,
diff --git a/xen/arch/x86/include/asm/guest-msr.h
b/xen/arch/x86/include/asm/guest-msr.h
index 5f0cb0a939..702f47fe1e 100644
--- a/xen/arch/x86/include/asm/guest-msr.h
+++ b/xen/arch/x86/include/asm/guest-msr.h
@@ -50,6 +50,7 @@ struct vcpu_msrs
};
} misc_features_enables;
+#ifdef CONFIG_VMTRACE
/*
* 0x00000560 ... 57x - MSR_RTIT_*
*
@@ -81,6 +82,7 @@ struct vcpu_msrs
};
};
} rtit;
+#endif
/*
* 0x000006e1 - MSR_PKRS - Protection Key Supervisor.
diff --git a/xen/arch/x86/include/asm/hvm/hvm.h
b/xen/arch/x86/include/asm/hvm/hvm.h
index af042ae858..7d9774df59 100644
--- a/xen/arch/x86/include/asm/hvm/hvm.h
+++ b/xen/arch/x86/include/asm/hvm/hvm.h
@@ -236,12 +236,14 @@ struct hvm_function_table {
int (*altp2m_vcpu_emulate_vmfunc)(const struct cpu_user_regs *regs);
#endif
+#ifdef CONFIG_VMTRACE
/* 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);
int (*vmtrace_reset)(struct vcpu *v);
+#endif
uint64_t (*get_reg)(struct vcpu *v, unsigned int reg);
void (*set_reg)(struct vcpu *v, unsigned int reg, uint64_t val);
@@ -741,6 +743,7 @@ static inline bool altp2m_vcpu_emulate_ve(struct vcpu *v)
bool altp2m_vcpu_emulate_ve(struct vcpu *v);
#endif /* CONFIG_ALTP2M */
+#ifdef CONFIG_VMTRACE
static inline int hvm_vmtrace_control(struct vcpu *v, bool enable, bool reset)
{
if ( hvm_funcs.vmtrace_control )
@@ -775,11 +778,20 @@ static inline int hvm_vmtrace_get_option(
return -EOPNOTSUPP;
}
+#else
+/*
+ * Function declaration(s) here are used without definition(s) to make compiler
+ * happy when VMTRACE=n, compiler DCE will eliminate unused code.
+ */
+int hvm_vmtrace_output_position(struct vcpu *v, uint64_t *pos);
+#endif
static inline int hvm_vmtrace_reset(struct vcpu *v)
{
+#ifdef CONFIG_VMTRACE
if ( hvm_funcs.vmtrace_reset )
return alternative_call(hvm_funcs.vmtrace_reset, v);
+#endif
return -EOPNOTSUPP;
}
@@ -937,28 +949,6 @@ 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;
-}
-
static inline uint64_t hvm_get_reg(struct vcpu *v, unsigned int reg)
{
ASSERT_UNREACHABLE();
diff --git a/xen/arch/x86/include/asm/hvm/vmx/vmcs.h
b/xen/arch/x86/include/asm/hvm/vmx/vmcs.h
index 8ff7c8045f..879ec10cef 100644
--- a/xen/arch/x86/include/asm/hvm/vmx/vmcs.h
+++ b/xen/arch/x86/include/asm/hvm/vmx/vmcs.h
@@ -154,8 +154,10 @@ struct vmx_vcpu {
/* Do we need to tolerate a spurious EPT_MISCONFIG VM exit? */
bool ept_spurious_misconfig;
+#ifdef CONFIG_VMTRACE
/* Processor Trace configured and enabled for the vcpu. */
bool ipt_active;
+#endif
/* Is the guest in real mode? */
uint8_t vmx_realmode;
diff --git a/xen/arch/x86/mm/mem_sharing.c b/xen/arch/x86/mm/mem_sharing.c
index b5a259af1d..5c7a0ff30e 100644
--- a/xen/arch/x86/mm/mem_sharing.c
+++ b/xen/arch/x86/mm/mem_sharing.c
@@ -1891,7 +1891,9 @@ static int fork(struct domain *cd, struct domain *d)
domain_pause(d);
cd->max_pages = d->max_pages;
*cd->arch.cpu_policy = *d->arch.cpu_policy;
+#ifdef CONFIG_VMTRACE
cd->vmtrace_size = d->vmtrace_size;
+#endif
cd->parent = d;
}
diff --git a/xen/arch/x86/vm_event.c b/xen/arch/x86/vm_event.c
index fc349270b9..112d2ef66d 100644
--- a/xen/arch/x86/vm_event.c
+++ b/xen/arch/x86/vm_event.c
@@ -253,7 +253,9 @@ void vm_event_fill_regs(vm_event_request_t *req)
req->data.regs.x86.shadow_gs = ctxt.shadow_gs;
req->data.regs.x86.dr6 = ctxt.dr6;
- if ( hvm_vmtrace_output_position(curr, &req->data.regs.x86.vmtrace_pos) !=
1 )
+ if ( IS_ENABLED(CONFIG_VMTRACE) &&
+ hvm_vmtrace_output_position(curr,
+ &req->data.regs.x86.vmtrace_pos) != 1 )
req->data.regs.x86.vmtrace_pos = ~0;
#endif
}
@@ -303,12 +305,12 @@ void vm_event_emulate_check(struct vcpu *v,
vm_event_response_t *rsp)
#endif
}
+#ifdef CONFIG_VMTRACE
void vm_event_reset_vmtrace(struct vcpu *v)
{
-#ifdef CONFIG_HVM
hvm_vmtrace_reset(v);
-#endif
}
+#endif
/*
* Local variables:
diff --git a/xen/common/domain.c b/xen/common/domain.c
index 163f7fc966..3fd907e274 100644
--- a/xen/common/domain.c
+++ b/xen/common/domain.c
@@ -135,7 +135,9 @@ struct vcpu *idle_vcpu[NR_CPUS] __read_mostly;
vcpu_info_t dummy_vcpu_info;
+#ifdef CONFIG_VMTRACE
bool __read_mostly vmtrace_available;
+#endif
bool __read_mostly vpmu_is_available;
@@ -358,6 +360,7 @@ static void free_vcpu_struct(struct vcpu *v)
static void vmtrace_free_buffer(struct vcpu *v)
{
+#ifdef CONFIG_VMTRACE
const struct domain *d = v->domain;
struct page_info *pg = v->vmtrace.pg;
unsigned int i;
@@ -372,10 +375,12 @@ static void vmtrace_free_buffer(struct vcpu *v)
put_page_alloc_ref(&pg[i]);
put_page_and_type(&pg[i]);
}
+#endif
}
static int vmtrace_alloc_buffer(struct vcpu *v)
{
+#ifdef CONFIG_VMTRACE
struct domain *d = v->domain;
struct page_info *pg;
unsigned int i;
@@ -417,6 +422,9 @@ static int vmtrace_alloc_buffer(struct vcpu *v)
}
return -ENODATA;
+#else
+ return 0;
+#endif
}
/*
@@ -884,7 +892,9 @@ struct domain *domain_create(domid_t domid,
ASSERT(!config->altp2m.nr);
#endif
+#ifdef CONFIG_VMTRACE
d->vmtrace_size = config->vmtrace_size;
+#endif
}
/* Sort out our idea of is_control_domain(). */
diff --git a/xen/common/memory.c b/xen/common/memory.c
index 9240a6005e..918510f287 100644
--- a/xen/common/memory.c
+++ b/xen/common/memory.c
@@ -1259,8 +1259,10 @@ static unsigned int resource_max_frames(const struct
domain *d,
case XENMEM_resource_ioreq_server:
return ioreq_server_max_frames(d);
+#ifdef CONFIG_VMTRACE
case XENMEM_resource_vmtrace_buf:
return d->vmtrace_size >> PAGE_SHIFT;
+#endif
default:
return 0;
@@ -1302,6 +1304,7 @@ static int acquire_ioreq_server(struct domain *d,
#endif
}
+#ifdef CONFIG_VMTRACE
static int acquire_vmtrace_buf(
struct domain *d, unsigned int id, unsigned int frame,
unsigned int nr_frames, xen_pfn_t mfn_list[])
@@ -1324,6 +1327,7 @@ static int acquire_vmtrace_buf(
return nr_frames;
}
+#endif
/*
* Returns -errno on error, or positive in the range [1, nr_frames] on
@@ -1342,8 +1346,10 @@ static int _acquire_resource(
case XENMEM_resource_ioreq_server:
return acquire_ioreq_server(d, id, frame, nr_frames, mfn_list);
+#ifdef CONFIG_VMTRACE
case XENMEM_resource_vmtrace_buf:
return acquire_vmtrace_buf(d, id, frame, nr_frames, mfn_list);
+#endif
default:
ASSERT_UNREACHABLE();
diff --git a/xen/common/vm_event.c b/xen/common/vm_event.c
index b2787c0108..cf0258223f 100644
--- a/xen/common/vm_event.c
+++ b/xen/common/vm_event.c
@@ -441,7 +441,8 @@ static int vm_event_resume(struct domain *d, struct
vm_event_domain *ved)
if ( rsp.flags & VM_EVENT_FLAG_GET_NEXT_INTERRUPT )
vm_event_monitor_next_interrupt(v);
- if ( rsp.flags & VM_EVENT_FLAG_RESET_VMTRACE )
+ if ( IS_ENABLED(CONFIG_VMTRACE) &&
+ (rsp.flags & VM_EVENT_FLAG_RESET_VMTRACE) )
vm_event_reset_vmtrace(v);
if ( rsp.flags & VM_EVENT_FLAG_VCPU_PAUSED )
diff --git a/xen/include/xen/domain.h b/xen/include/xen/domain.h
index 273717c31b..627ca0e071 100644
--- a/xen/include/xen/domain.h
+++ b/xen/include/xen/domain.h
@@ -183,7 +183,11 @@ void vnuma_destroy(struct vnuma_info *vnuma);
static inline void vnuma_destroy(struct vnuma_info *vnuma) { ASSERT(!vnuma); }
#endif
+#ifdef CONFIG_VMTRACE
extern bool vmtrace_available;
+#else
+#define vmtrace_available false
+#endif
extern bool vpmu_is_available;
diff --git a/xen/include/xen/sched.h b/xen/include/xen/sched.h
index 735d5b76b4..1268632344 100644
--- a/xen/include/xen/sched.h
+++ b/xen/include/xen/sched.h
@@ -300,9 +300,11 @@ struct vcpu
/* vPCI per-vCPU area, used to store data for long running operations. */
struct vpci_vcpu vpci;
+#ifdef CONFIG_VMTRACE
struct {
struct page_info *pg; /* One contiguous allocation of d->vmtrace_size
*/
} vmtrace;
+#endif
struct arch_vcpu arch;
@@ -626,7 +628,9 @@ struct domain
unsigned int nr_altp2m; /* Number of altp2m tables. */
#endif
+#ifdef CONFIG_VMTRACE
unsigned int vmtrace_size; /* Buffer size in bytes, or 0 to disable. */
+#endif
#ifdef CONFIG_ARGO
/* Argo interdomain communication support */
--
generated by git-patchbot for /home/xen/git/xen.git#master
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