diff mbox series

[1/6] target/i386/kvm: Add feature bit definitions for KVM CPUID

Message ID 20240426100716.2111688-2-zhao1.liu@intel.com (mailing list archive)
State New, archived
Headers show
Series target/i386: Misc cleanup on KVM PV defs and outdated comments | expand

Commit Message

Zhao Liu April 26, 2024, 10:07 a.m. UTC 
Add feature definiations for KVM_CPUID_FEATURES in CPUID (
CPUID[4000_0001].EAX and CPUID[4000_0001].EDX), to get rid of lots of
offset calculations.

Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
---
v2: Changed the prefix from CPUID_FEAT_KVM_* to CPUID_KVM_*. (Xiaoyao)
---
 hw/i386/kvm/clock.c   |  5 ++---
 target/i386/cpu.h     | 23 +++++++++++++++++++++++
 target/i386/kvm/kvm.c | 28 ++++++++++++++--------------
 3 files changed, 39 insertions(+), 17 deletions(-)

Comments

Zide Chen April 26, 2024, 5:23 p.m. UTC | #1 
On 4/26/2024 3:07 AM, Zhao Liu wrote:
> Add feature definiations for KVM_CPUID_FEATURES in CPUID (
> CPUID[4000_0001].EAX and CPUID[4000_0001].EDX), to get rid of lots of
> offset calculations.
> 
> Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
> ---
> v2: Changed the prefix from CPUID_FEAT_KVM_* to CPUID_KVM_*. (Xiaoyao)
> ---
>  hw/i386/kvm/clock.c   |  5 ++---
>  target/i386/cpu.h     | 23 +++++++++++++++++++++++
>  target/i386/kvm/kvm.c | 28 ++++++++++++++--------------
>  3 files changed, 39 insertions(+), 17 deletions(-)
> 
> diff --git a/hw/i386/kvm/clock.c b/hw/i386/kvm/clock.c
> index 40aa9a32c32c..ce416c05a3d0 100644
> --- a/hw/i386/kvm/clock.c
> +++ b/hw/i386/kvm/clock.c
> @@ -27,7 +27,6 @@
>  #include "qapi/error.h"
>  
>  #include <linux/kvm.h>
> -#include "standard-headers/asm-x86/kvm_para.h"
>  #include "qom/object.h"
>  
>  #define TYPE_KVM_CLOCK "kvmclock"
> @@ -334,8 +333,8 @@ void kvmclock_create(bool create_always)
>  
>      assert(kvm_enabled());
>      if (create_always ||
> -        cpu->env.features[FEAT_KVM] & ((1ULL << KVM_FEATURE_CLOCKSOURCE) |
> -                                       (1ULL << KVM_FEATURE_CLOCKSOURCE2))) {
> +        cpu->env.features[FEAT_KVM] & (CPUID_KVM_CLOCK |
> +                                       CPUID_KVM_CLOCK2)) {

To achieve this purpose, how about doing the alternative to define an
API similar to KVM's guest_pv_has()?

xxxx_has() is simpler and clearer than "features[] & CPUID_xxxxx",
additionally, this helps to keep the definitions identical to KVM, more
readable and easier for future maintenance.
Zhao Liu May 6, 2024, 2:54 a.m. UTC | #2 
Hi Zide,

On Fri, Apr 26, 2024 at 10:23:27AM -0700, Chen, Zide wrote:
> Date: Fri, 26 Apr 2024 10:23:27 -0700
> From: "Chen, Zide" <zide.chen@intel.com>
> Subject: Re: [PATCH 1/6] target/i386/kvm: Add feature bit definitions for
>  KVM CPUID
> 
> On 4/26/2024 3:07 AM, Zhao Liu wrote:
> > Add feature definiations for KVM_CPUID_FEATURES in CPUID (
> > CPUID[4000_0001].EAX and CPUID[4000_0001].EDX), to get rid of lots of
> > offset calculations.
> > 
> > Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
> > ---
> > v2: Changed the prefix from CPUID_FEAT_KVM_* to CPUID_KVM_*. (Xiaoyao)
> > ---
> >  hw/i386/kvm/clock.c   |  5 ++---
> >  target/i386/cpu.h     | 23 +++++++++++++++++++++++
> >  target/i386/kvm/kvm.c | 28 ++++++++++++++--------------
> >  3 files changed, 39 insertions(+), 17 deletions(-)
> > 
> > diff --git a/hw/i386/kvm/clock.c b/hw/i386/kvm/clock.c
> > index 40aa9a32c32c..ce416c05a3d0 100644
> > --- a/hw/i386/kvm/clock.c
> > +++ b/hw/i386/kvm/clock.c
> > @@ -27,7 +27,6 @@
> >  #include "qapi/error.h"
> >  
> >  #include <linux/kvm.h>
> > -#include "standard-headers/asm-x86/kvm_para.h"
> >  #include "qom/object.h"
> >  
> >  #define TYPE_KVM_CLOCK "kvmclock"
> > @@ -334,8 +333,8 @@ void kvmclock_create(bool create_always)
> >  
> >      assert(kvm_enabled());
> >      if (create_always ||
> > -        cpu->env.features[FEAT_KVM] & ((1ULL << KVM_FEATURE_CLOCKSOURCE) |
> > -                                       (1ULL << KVM_FEATURE_CLOCKSOURCE2))) {
> > +        cpu->env.features[FEAT_KVM] & (CPUID_KVM_CLOCK |
> > +                                       CPUID_KVM_CLOCK2)) {
> 
> To achieve this purpose, how about doing the alternative to define an
> API similar to KVM's guest_pv_has()?
>
> xxxx_has() is simpler and clearer than "features[] & CPUID_xxxxx",
> additionally, this helps to keep the definitions identical to KVM, more
> readable and easier for future maintenance.

Yes, it's a clearer way! I can explore the xxxx_has() pattern in another
series and try to expand it to more CPUID leaves.

Thanks,
Zhao
diff mbox series

Patch

diff --git a/hw/i386/kvm/clock.c b/hw/i386/kvm/clock.c
index 40aa9a32c32c..ce416c05a3d0 100644
--- a/hw/i386/kvm/clock.c
+++ b/hw/i386/kvm/clock.c
@@ -27,7 +27,6 @@ 
 #include "qapi/error.h"
 
 #include <linux/kvm.h>
-#include "standard-headers/asm-x86/kvm_para.h"
 #include "qom/object.h"
 
 #define TYPE_KVM_CLOCK "kvmclock"
@@ -334,8 +333,8 @@  void kvmclock_create(bool create_always)
 
     assert(kvm_enabled());
     if (create_always ||
-        cpu->env.features[FEAT_KVM] & ((1ULL << KVM_FEATURE_CLOCKSOURCE) |
-                                       (1ULL << KVM_FEATURE_CLOCKSOURCE2))) {
+        cpu->env.features[FEAT_KVM] & (CPUID_KVM_CLOCK |
+                                       CPUID_KVM_CLOCK2)) {
         sysbus_create_simple(TYPE_KVM_CLOCK, -1, NULL);
     }
 }
diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index 6112e27bfd5c..caa32a91346b 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -27,6 +27,7 @@ 
 #include "qapi/qapi-types-common.h"
 #include "qemu/cpu-float.h"
 #include "qemu/timer.h"
+#include "standard-headers/asm-x86/kvm_para.h"
 
 #define XEN_NR_VIRQS 24
 
@@ -951,6 +952,28 @@  uint64_t x86_cpu_get_supported_feature_word(FeatureWord w,
 /* Packets which contain IP payload have LIP values */
 #define CPUID_14_0_ECX_LIP              (1U << 31)
 
+/* (Old) KVM paravirtualized clocksource */
+#define CPUID_KVM_CLOCK            (1U << KVM_FEATURE_CLOCKSOURCE)
+/* (New) KVM specific paravirtualized clocksource */
+#define CPUID_KVM_CLOCK2           (1U << KVM_FEATURE_CLOCKSOURCE2)
+/* KVM asynchronous page fault */
+#define CPUID_KVM_ASYNCPF          (1U << KVM_FEATURE_ASYNC_PF)
+/* KVM stolen (when guest vCPU is not running) time accounting */
+#define CPUID_KVM_STEAL_TIME       (1U << KVM_FEATURE_STEAL_TIME)
+/* KVM paravirtualized end-of-interrupt signaling */
+#define CPUID_KVM_PV_EOI           (1U << KVM_FEATURE_PV_EOI)
+/* KVM paravirtualized spinlocks support */
+#define CPUID_KVM_PV_UNHALT        (1U << KVM_FEATURE_PV_UNHALT)
+/* KVM host-side polling on HLT control from the guest */
+#define CPUID_KVM_POLL_CONTROL     (1U << KVM_FEATURE_POLL_CONTROL)
+/* KVM interrupt based asynchronous page fault*/
+#define CPUID_KVM_ASYNCPF_INT      (1U << KVM_FEATURE_ASYNC_PF_INT)
+/* KVM 'Extended Destination ID' support for external interrupts */
+#define CPUID_KVM_MSI_EXT_DEST_ID  (1U << KVM_FEATURE_MSI_EXT_DEST_ID)
+
+/* Hint to KVM that vCPUs expect never preempted for an unlimited time */
+#define CPUID_KVM_HINTS_REALTIME    (1U << KVM_HINTS_REALTIME)
+
 /* CLZERO instruction */
 #define CPUID_8000_0008_EBX_CLZERO      (1U << 0)
 /* Always save/restore FP error pointers */
diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
index c5943605ee3a..d9e03891113f 100644
--- a/target/i386/kvm/kvm.c
+++ b/target/i386/kvm/kvm.c
@@ -527,13 +527,13 @@  uint32_t kvm_arch_get_supported_cpuid(KVMState *s, uint32_t function,
          * be enabled without the in-kernel irqchip
          */
         if (!kvm_irqchip_in_kernel()) {
-            ret &= ~(1U << KVM_FEATURE_PV_UNHALT);
+            ret &= ~CPUID_KVM_PV_UNHALT;
         }
         if (kvm_irqchip_is_split()) {
-            ret |= 1U << KVM_FEATURE_MSI_EXT_DEST_ID;
+            ret |= CPUID_KVM_MSI_EXT_DEST_ID;
         }
     } else if (function == KVM_CPUID_FEATURES && reg == R_EDX) {
-        ret |= 1U << KVM_HINTS_REALTIME;
+        ret |= CPUID_KVM_HINTS_REALTIME;
     }
 
     return ret;
@@ -3377,20 +3377,20 @@  static int kvm_put_msrs(X86CPU *cpu, int level)
         kvm_msr_entry_add(cpu, MSR_IA32_TSC, env->tsc);
         kvm_msr_entry_add(cpu, MSR_KVM_SYSTEM_TIME, env->system_time_msr);
         kvm_msr_entry_add(cpu, MSR_KVM_WALL_CLOCK, env->wall_clock_msr);
-        if (env->features[FEAT_KVM] & (1 << KVM_FEATURE_ASYNC_PF_INT)) {
+        if (env->features[FEAT_KVM] & CPUID_KVM_ASYNCPF_INT) {
             kvm_msr_entry_add(cpu, MSR_KVM_ASYNC_PF_INT, env->async_pf_int_msr);
         }
-        if (env->features[FEAT_KVM] & (1 << KVM_FEATURE_ASYNC_PF)) {
+        if (env->features[FEAT_KVM] & CPUID_KVM_ASYNCPF) {
             kvm_msr_entry_add(cpu, MSR_KVM_ASYNC_PF_EN, env->async_pf_en_msr);
         }
-        if (env->features[FEAT_KVM] & (1 << KVM_FEATURE_PV_EOI)) {
+        if (env->features[FEAT_KVM] & CPUID_KVM_PV_EOI) {
             kvm_msr_entry_add(cpu, MSR_KVM_PV_EOI_EN, env->pv_eoi_en_msr);
         }
-        if (env->features[FEAT_KVM] & (1 << KVM_FEATURE_STEAL_TIME)) {
+        if (env->features[FEAT_KVM] & CPUID_KVM_STEAL_TIME) {
             kvm_msr_entry_add(cpu, MSR_KVM_STEAL_TIME, env->steal_time_msr);
         }
 
-        if (env->features[FEAT_KVM] & (1 << KVM_FEATURE_POLL_CONTROL)) {
+        if (env->features[FEAT_KVM] & CPUID_KVM_POLL_CONTROL) {
             kvm_msr_entry_add(cpu, MSR_KVM_POLL_CONTROL, env->poll_control_msr);
         }
 
@@ -3842,19 +3842,19 @@  static int kvm_get_msrs(X86CPU *cpu)
 #endif
     kvm_msr_entry_add(cpu, MSR_KVM_SYSTEM_TIME, 0);
     kvm_msr_entry_add(cpu, MSR_KVM_WALL_CLOCK, 0);
-    if (env->features[FEAT_KVM] & (1 << KVM_FEATURE_ASYNC_PF_INT)) {
+    if (env->features[FEAT_KVM] & CPUID_KVM_ASYNCPF_INT) {
         kvm_msr_entry_add(cpu, MSR_KVM_ASYNC_PF_INT, 0);
     }
-    if (env->features[FEAT_KVM] & (1 << KVM_FEATURE_ASYNC_PF)) {
+    if (env->features[FEAT_KVM] & CPUID_KVM_ASYNCPF) {
         kvm_msr_entry_add(cpu, MSR_KVM_ASYNC_PF_EN, 0);
     }
-    if (env->features[FEAT_KVM] & (1 << KVM_FEATURE_PV_EOI)) {
+    if (env->features[FEAT_KVM] & CPUID_KVM_PV_EOI) {
         kvm_msr_entry_add(cpu, MSR_KVM_PV_EOI_EN, 0);
     }
-    if (env->features[FEAT_KVM] & (1 << KVM_FEATURE_STEAL_TIME)) {
+    if (env->features[FEAT_KVM] & CPUID_KVM_STEAL_TIME) {
         kvm_msr_entry_add(cpu, MSR_KVM_STEAL_TIME, 0);
     }
-    if (env->features[FEAT_KVM] & (1 << KVM_FEATURE_POLL_CONTROL)) {
+    if (env->features[FEAT_KVM] & CPUID_KVM_POLL_CONTROL) {
         kvm_msr_entry_add(cpu, MSR_KVM_POLL_CONTROL, 1);
     }
     if (has_architectural_pmu_version > 0) {
@@ -5487,7 +5487,7 @@  uint64_t kvm_swizzle_msi_ext_dest_id(uint64_t address)
         return address;
     }
     env = &X86_CPU(first_cpu)->env;
-    if (!(env->features[FEAT_KVM] & (1 << KVM_FEATURE_MSI_EXT_DEST_ID))) {
+    if (!(env->features[FEAT_KVM] & CPUID_KVM_MSI_EXT_DEST_ID)) {
         return address;
     }