If VM runs in kvm mode, VM mode is added in IOCSR feature register.
So guest can detect kvm hypervisor type and enable possible pv functions.

Signed-off-by: Bibo Mao <maobibo@loongson.cn>
---
 hw/loongarch/virt.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/hw/loongarch/virt.c b/hw/loongarch/virt.c
index d87d9be576..44bcf25aee 100644
--- a/hw/loongarch/virt.c
+++ b/hw/loongarch/virt.c
@@ -10,6 +10,7 @@
 #include "qapi/error.h"
 #include "hw/boards.h"
 #include "hw/char/serial.h"
+#include "sysemu/kvm.h"
 #include "sysemu/sysemu.h"
 #include "sysemu/qtest.h"
 #include "sysemu/runstate.h"
@@ -840,18 +841,23 @@ static void virt_iocsr_misc_write(void *opaque, hwaddr addr,
 
 static uint64_t virt_iocsr_misc_read(void *opaque, hwaddr addr, unsigned size)
 {
+    uint64_t ret;
+
     switch (addr) {
     case VERSION_REG:
         return 0x11ULL;
     case FEATURE_REG:
-        return 1ULL << IOCSRF_MSI | 1ULL << IOCSRF_EXTIOI |
-               1ULL << IOCSRF_CSRIPI;
+        ret = BIT(IOCSRF_MSI) | BIT(IOCSRF_EXTIOI) | BIT(IOCSRF_CSRIPI);
+        if (kvm_enabled()) {
+            ret |= BIT(IOCSRF_VM);
+        }
+        return ret;
     case VENDOR_REG:
         return 0x6e6f73676e6f6f4cULL; /* "Loongson" */
     case CPUNAME_REG:
         return 0x303030354133ULL;     /* "3A5000" */
     case MISC_FUNC_REG:
-        return 1ULL << IOCSRM_EXTIOI_EN;
+        return BIT_ULL(IOCSRM_EXTIOI_EN);
     }
     return 0ULL;
 }
-- 
2.39.3

在 2024/5/14 上午10:51, Bibo Mao 写道:
> If VM runs in kvm mode, VM mode is added in IOCSR feature register.
> So guest can detect kvm hypervisor type and enable possible pv functions.
>
> Signed-off-by: Bibo Mao <maobibo@loongson.cn>
> ---
Reviewed-by: Song Gao <gaosong@loongson.cn>

Thanks.
Song Gao
>   hw/loongarch/virt.c | 12 +++++++++---
>   1 file changed, 9 insertions(+), 3 deletions(-)
>
> diff --git a/hw/loongarch/virt.c b/hw/loongarch/virt.c
> index d87d9be576..44bcf25aee 100644
> --- a/hw/loongarch/virt.c
> +++ b/hw/loongarch/virt.c
> @@ -10,6 +10,7 @@
>   #include "qapi/error.h"
>   #include "hw/boards.h"
>   #include "hw/char/serial.h"
> +#include "sysemu/kvm.h"
>   #include "sysemu/sysemu.h"
>   #include "sysemu/qtest.h"
>   #include "sysemu/runstate.h"
> @@ -840,18 +841,23 @@ static void virt_iocsr_misc_write(void *opaque, hwaddr addr,
>   
>   static uint64_t virt_iocsr_misc_read(void *opaque, hwaddr addr, unsigned size)
>   {
> +    uint64_t ret;
> +
>       switch (addr) {
>       case VERSION_REG:
>           return 0x11ULL;
>       case FEATURE_REG:
> -        return 1ULL << IOCSRF_MSI | 1ULL << IOCSRF_EXTIOI |
> -               1ULL << IOCSRF_CSRIPI;
> +        ret = BIT(IOCSRF_MSI) | BIT(IOCSRF_EXTIOI) | BIT(IOCSRF_CSRIPI);
> +        if (kvm_enabled()) {
> +            ret |= BIT(IOCSRF_VM);
> +        }
> +        return ret;
>       case VENDOR_REG:
>           return 0x6e6f73676e6f6f4cULL; /* "Loongson" */
>       case CPUNAME_REG:
>           return 0x303030354133ULL;     /* "3A5000" */
>       case MISC_FUNC_REG:
> -        return 1ULL << IOCSRM_EXTIOI_EN;
> +        return BIT_ULL(IOCSRM_EXTIOI_EN);
>       }
>       return 0ULL;
>   }