Add machine option and QMP commands to configure TSC deadline
timer advancement.
Signed-off-by: Marcelo Tosatti <mtosatti@xxxxxxxxxx>
---
monitor.c | 15 ++++++++++
qapi-schema.json | 29 +++++++++++++++++++
qmp-commands.hx | 48 ++++++++++++++++++++++++++++++++
target-i386/kvm.c | 80 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
vl.c | 4 ++
5 files changed, 176 insertions(+)
Index: qemu.tscdeadline/qapi-schema.json
===================================================================
--- qemu.tscdeadline.orig/qapi-schema.json
+++ qemu.tscdeadline/qapi-schema.json
@@ -3515,3 +3515,32 @@
# Since: 2.1
##
{ 'command': 'rtc-reset-reinjection' }
+
+##
+# @set-lapic-tscdeadline-advance
+#
+# This command sets the TSC deadline timer advancement.
+# This value will be subtracted from the expiration time
+# of the high resolution timer which emulates
+# TSC deadline timer.
+#
+# Useful to achieve low timer latencies.
+#
+# Only supported by KVM acceleration.
+#
+# Since: 2.3
+##
+{ 'command': 'set-lapic-tscdeadline-advance',
+ 'data': { 'advance':'int' }
+}
+
+##
+# @get-lapic-tscdeadline-advance
+#
+# This command gets the TSC deadline timer advancement.
+#
+# Only supported by KVM acceleration.
+#
+# Since: 2.3
+##
+{ 'command': 'get-lapic-tscdeadline-advance', 'returns': 'int' }
Index: qemu.tscdeadline/qmp-commands.hx
===================================================================
--- qemu.tscdeadline.orig/qmp-commands.hx
+++ qemu.tscdeadline/qmp-commands.hx
@@ -3854,3 +3854,51 @@ Move mouse pointer to absolute coordinat
<- { "return": {} }
EQMP
+
+ {
+ .name = "set-lapic-tscdeadline-advance",
+ .args_type = "advance:i",
+ .mhandler.cmd_new = qmp_marshal_input_set_lapic_tscdeadline_advance,
+ },
+
+SQMP
+set-lapic-tscdeadline-advance
+-----------------------------
+
+Set LAPIC tscdeadline timer advancement, in nanoseconds.
+
+Arguments:
+
+- "advance": LAPIC tscdeadline timer advancement (json-int)
+
+Example:
+
+-> { "execute": "set-lapic-tscdeadline-advance 1000" }
+<- { "return": {} }
+
+EQMP
+
+ {
+ .name = "get-lapic-tscdeadline-advance",
+ .args_type = "",
+ .mhandler.cmd_new = qmp_marshal_input_get_lapic_tscdeadline_advance,
+ },
+
+SQMP
+get-lapic-tscdeadline-advance
+-----------------------------
+
+Get LAPIC tscdeadline timer advancement, in nanoseconds.
+
+Arguments: None.
+
+returns a json-object with the following information:
+- "value" : json-int
+
+Example:
+
+-> { "execute": "get-lapic-tscdeadline-advance" }
+<- { "return": {1000} }
+
+EQMP
+
Index: qemu.tscdeadline/vl.c
===================================================================
--- qemu.tscdeadline.orig/vl.c
+++ qemu.tscdeadline/vl.c
@@ -387,6 +387,10 @@ static QemuOptsList qemu_machine_opts =
.name = "iommu",
.type = QEMU_OPT_BOOL,
.help = "Set on/off to enable/disable Intel IOMMU (VT-d)",
+ },{
+ .name = "lapic-tscdeadline-advance",
+ .type = QEMU_OPT_NUMBER,
+ .help = "Set lapic tscdeadline timer advance",
},
{ /* End of list */ }
},
Index: qemu.tscdeadline/target-i386/kvm.c
===================================================================
--- qemu.tscdeadline.orig/target-i386/kvm.c
+++ qemu.tscdeadline/target-i386/kvm.c
@@ -37,6 +37,7 @@
#include "hw/pci/pci.h"
#include "migration/migration.h"
#include "qapi/qmp/qerror.h"
+#include "qmp-commands.h"
//#define DEBUG_KVM
@@ -84,6 +85,10 @@ static bool has_msr_mtrr;
static bool has_msr_architectural_pmu;
static uint32_t num_architectural_pmu_counters;
+static struct lapic_tscdeadline_advance {
+ unsigned int advance_ns;
+} lapic_tscdeadline_advance;
+
bool kvm_allows_irq0_override(void)
{
return !kvm_irqchip_in_kernel() || kvm_has_gsi_routing();
@@ -835,12 +840,32 @@ static int kvm_get_supported_msrs(KVMSta
return ret;
}
+static int kvm_set_lapic_tscdeadline(KVMState *s, uint32_t advance)
+{
+ struct kvm_tscdeadline_advance adv;
+ int ret = 0;
+
+ memset(&adv, 0, sizeof(adv));
+
+ adv.timer_advance = advance;
+
+ ret = kvm_vm_ioctl(s, KVM_SET_TSCDEADLINE_ADVANCE, &adv);
+ if (ret < 0) {
+ return ret;
+ }
+
+ lapic_tscdeadline_advance.advance_ns = advance;
+
+ return ret;
+}
+
int kvm_arch_init(KVMState *s)
{
uint64_t identity_base = 0xfffbc000;
uint64_t shadow_mem;
int ret;
struct utsname utsname;
+ uint32_t lapic_advance_ns;
ret = kvm_get_supported_msrs(s);
if (ret < 0) {
@@ -894,9 +919,40 @@ int kvm_arch_init(KVMState *s)
return ret;
}
}
+
+ lapic_advance_ns = qemu_opt_get_number(qemu_get_machine_opts(),
+ "lapic-tscdeadline-advance",
+ 0);
+ if (lapic_advance_ns) {
+ ret = kvm_set_lapic_tscdeadline(s, lapic_advance_ns);
+ if (ret) {
+ fprintf(stderr, "Set tscdeadline advance failed: %s\n",
+ strerror(-ret));
+ return ret;
+ }
+ }
+
+
return 0;
}
+int64_t qmp_get_lapic_tscdeadline_advance(Error **errp)
+{
+ return lapic_tscdeadline_advance.advance_ns;
+}
+
+void qmp_set_lapic_tscdeadline_advance(int64_t advance, Error **errp)
+{
+ KVMState *s = kvm_state;
+ int ret;
+
+ ret = kvm_set_lapic_tscdeadline(s, advance);
+ if (ret) {
+ error_setg_errno(errp, ret, "set lapic tscdeadline failed");
+ return;
+ }
+}
+
static void set_v8086_seg(struct kvm_segment *lhs, const SegmentCache *rhs)
{
lhs->selector = rhs->selector;
Index: qemu.tscdeadline/monitor.c
===================================================================
--- qemu.tscdeadline.orig/monitor.c
+++ qemu.tscdeadline/monitor.c
@@ -5447,3 +5447,18 @@ void qmp_rtc_reset_reinjection(Error **e
error_set(errp, QERR_FEATURE_DISABLED, "rtc-reset-reinjection");
}
#endif
+
+#if !defined (TARGET_I386) || !defined (CONFIG_KVM)
+int64_t qmp_get_lapic_tscdeadline_advance(Error **errp)
+{
+ error_set(errp, QERR_FEATURE_DISABLED, "get-lapic-tscdeadline-advance");
+
+ return 0;
+}
+
+void qmp_set_lapic_tscdeadline_advance(int64_t advance, Error **errp)
+{
+ error_set(errp, QERR_FEATURE_DISABLED, "set-lapic-tscdeadline-advance");
+}
+#endif
+
Index: qemu.tscdeadline/include/hw/boards.h
===================================================================
--- qemu.tscdeadline.orig/include/hw/boards.h
+++ qemu.tscdeadline/include/hw/boards.h
@@ -133,6 +133,7 @@ struct MachineState {
bool usb;
char *firmware;
bool iommu;
+ int lapi_tscdeadline_advance;
ram_addr_t ram_size;
ram_addr_t maxram_size;
Index: qemu.tscdeadline/qemu-options.hx
===================================================================
--- qemu.tscdeadline.orig/qemu-options.hx
+++ qemu.tscdeadline/qemu-options.hx
@@ -37,7 +37,8 @@ DEF("machine", HAS_ARG, QEMU_OPTION_mach
" kvm_shadow_mem=size of KVM shadow MMU\n"
" dump-guest-core=on|off include guest memory in a core dump (default=on)\n"
" mem-merge=on|off controls memory merge support (default: on)\n"
- " iommu=on|off controls emulated Intel IOMMU (VT-d) support (default=off)\n",
+ " iommu=on|off controls emulated Intel IOMMU (VT-d) support (default=off)\n"
+ " lapic-tscdeadline-advance=value controls LAPIC tscdeadline timer advancement (default=0)\n",
QEMU_ARCH_ALL)
STEXI
@item -machine [type=]@var{name}[,prop=@var{value}[,...]]
@@ -66,6 +67,8 @@ the host, de-duplicates identical memory
(enabled by default).
@item iommu=on|off
Enables or disables emulated Intel IOMMU (VT-d) support. The default is off.
+@item lapic-tscdeadline-advance=value
+Defines the advancement of LAPIC TSC deadline timer, in nanoseconds.
@end table
ETEXI
Index: qemu.tscdeadline/hw/core/machine.c
===================================================================
--- qemu.tscdeadline.orig/hw/core/machine.c
+++ qemu.tscdeadline/hw/core/machine.c
@@ -72,6 +72,35 @@ static void machine_set_kvm_shadow_mem(O
ms->kvm_shadow_mem = value;
}
+static void machine_get_lapic_tscdeadline_advance(Object *obj, Visitor *v,
+ void *opaque,
+ const char *name,
+ Error **errp)
+{
+ MachineState *ms = MACHINE(obj);
+ int64_t value = ms->kvm_shadow_mem;
+
+ visit_type_int(v, &value, name, errp);
+}
+
+static void machine_set_lapic_tscdeadline_advance(Object *obj, Visitor *v,
+ void *opaque,
+ const char *name,
+ Error **errp)
+{
+ MachineState *ms = MACHINE(obj);
+ Error *error = NULL;
+ int64_t value;
+
+ visit_type_int(v, &value, name, &error);
+ if (error) {
+ error_propagate(errp, error);
+ return;
+ }
+
+ ms->lapi_tscdeadline_advance = value;
+}
+
static char *machine_get_kernel(Object *obj, Error **errp)
{
MachineState *ms = MACHINE(obj);
@@ -299,6 +328,10 @@ static void machine_initfn(Object *obj)
machine_get_kvm_shadow_mem,
machine_set_kvm_shadow_mem,
NULL, NULL, NULL);
+ object_property_add(obj, "lapic-tscdeadline-advance", "int",
+ machine_get_lapic_tscdeadline_advance,
+ machine_set_lapic_tscdeadline_advance,
+ NULL, NULL, NULL);
object_property_add_str(obj, "kernel",
machine_get_kernel, machine_set_kernel, NULL);
object_property_add_str(obj, "initrd",
--
To unsubscribe from this list: send the line "unsubscribe kvm" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
