[Qemu-devel] [PATCH] KVM: x86: Refactor persistent CPU state

[Qemu-devel] [PATCH] KVM: x86: Refactor persistent CPU state

[Jan Kiszka]

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This patch aligns the KVM-related layout and encoding of the CPU state
to be saved to disk or migrated with qemu-kvm. The major differences are
reordering of fields and a compressed interrupt_bitmap into a single
number as there can be no more than one pending IRQ at a time.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
---

 target-i386/machine.c |   30 +++++++++++++++++++++++-------
 1 files changed, 23 insertions(+), 7 deletions(-)

diff --git a/target-i386/machine.c b/target-i386/machine.c
index bb8b9db..259302c 100644
--- a/target-i386/machine.c
+++ b/target-i386/machine.c
@@ -28,7 +28,8 @@ void cpu_save(QEMUFile *f, void *opaque)
     uint16_t fptag, fpus, fpuc, fpregs_format;
     uint32_t hflags;
     int32_t a20_mask;
-    int i;
+    int32_t pending_irq;
+    int i, bit;
 
     cpu_synchronize_state(env, 0);
 
@@ -141,11 +142,21 @@ void cpu_save(QEMUFile *f, void *opaque)
         qemu_put_be64s(f, &env->mtrr_var[i].mask);
     }
 
-    for (i = 0; i < sizeof(env->interrupt_bitmap)/8; i++) {
-        qemu_put_be64s(f, &env->interrupt_bitmap[i]);
+    /* KVM-related states */
+
+    /* There can only be one pending IRQ set in the bitmap at a time, so try
+       to find it and save its number instead (-1 for none). */
+    pending_irq = -1;
+    for (i = 0; i < ARRAY_SIZE(env->interrupt_bitmap); i++) {
+        bit = ffsll(env->interrupt_bitmap[i]);
+        if (bit) {
+            pending_irq = i * 64 + bit - 1;
+            break;
+        }
     }
-    qemu_put_be64s(f, &env->tsc);
+    qemu_put_sbe32s(f, &pending_irq);
     qemu_put_be32s(f, &env->mp_state);
+    qemu_put_be64s(f, &env->tsc);
 }
 
 #ifdef USE_X86LDOUBLE
@@ -179,6 +190,7 @@ int cpu_load(QEMUFile *f, void *opaque, int version_id)
     uint32_t hflags;
     uint16_t fpus, fpuc, fptag, fpregs_format;
     int32_t a20_mask;
+    int32_t pending_irq;
 
     if (version_id < 3 || version_id > CPU_SAVE_VERSION)
         return -EINVAL;
@@ -324,12 +336,16 @@ int cpu_load(QEMUFile *f, void *opaque, int version_id)
             qemu_get_be64s(f, &env->mtrr_var[i].mask);
         }
     }
+
     if (version_id >= 9) {
-        for (i = 0; i < sizeof(env->interrupt_bitmap)/8; i++) {
-            qemu_get_be64s(f, &env->interrupt_bitmap[i]);
+        qemu_get_sbe32s(f, &pending_irq);
+        memset(&env->interrupt_bitmap, 0, sizeof(env->interrupt_bitmap));
+        if (pending_irq >= 0) {
+            env->interrupt_bitmap[pending_irq / 64] |=
+                (uint64_t)1 << (pending_irq % 64);
         }
-        qemu_get_be64s(f, &env->tsc);
         qemu_get_be32s(f, &env->mp_state);
+        qemu_get_be64s(f, &env->tsc);
     }
 
     /* XXX: ensure compatiblity for halted bit ? */


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[Qemu-devel] Re: [PATCH] KVM: x86: Refactor persistent CPU state

[Anthony Liguori]

Jan Kiszka wrote:
> This patch aligns the KVM-related layout and encoding of the CPU state
> to be saved to disk or migrated with qemu-kvm. The major differences are
> reordering of fields and a compressed interrupt_bitmap into a single
> number as there can be no more than one pending IRQ at a time.
>
> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
>   

We need a version bump, no?

Regards,

Anthony Liguori

> ---
>
>  target-i386/machine.c |   30 +++++++++++++++++++++++-------
>  1 files changed, 23 insertions(+), 7 deletions(-)
>
> diff --git a/target-i386/machine.c b/target-i386/machine.c
> index bb8b9db..259302c 100644
> --- a/target-i386/machine.c
> +++ b/target-i386/machine.c
> @@ -28,7 +28,8 @@ void cpu_save(QEMUFile *f, void *opaque)
>      uint16_t fptag, fpus, fpuc, fpregs_format;
>      uint32_t hflags;
>      int32_t a20_mask;
> -    int i;
> +    int32_t pending_irq;
> +    int i, bit;
>  
>      cpu_synchronize_state(env, 0);
>  
> @@ -141,11 +142,21 @@ void cpu_save(QEMUFile *f, void *opaque)
>          qemu_put_be64s(f, &env->mtrr_var[i].mask);
>      }
>  
> -    for (i = 0; i < sizeof(env->interrupt_bitmap)/8; i++) {
> -        qemu_put_be64s(f, &env->interrupt_bitmap[i]);
> +    /* KVM-related states */
> +
> +    /* There can only be one pending IRQ set in the bitmap at a time, so try
> +       to find it and save its number instead (-1 for none). */
> +    pending_irq = -1;
> +    for (i = 0; i < ARRAY_SIZE(env->interrupt_bitmap); i++) {
> +        bit = ffsll(env->interrupt_bitmap[i]);
> +        if (bit) {
> +            pending_irq = i * 64 + bit - 1;
> +            break;
> +        }
>      }
> -    qemu_put_be64s(f, &env->tsc);
> +    qemu_put_sbe32s(f, &pending_irq);
>      qemu_put_be32s(f, &env->mp_state);
> +    qemu_put_be64s(f, &env->tsc);
>  }
>  
>  #ifdef USE_X86LDOUBLE
> @@ -179,6 +190,7 @@ int cpu_load(QEMUFile *f, void *opaque, int version_id)
>      uint32_t hflags;
>      uint16_t fpus, fpuc, fptag, fpregs_format;
>      int32_t a20_mask;
> +    int32_t pending_irq;
>  
>      if (version_id < 3 || version_id > CPU_SAVE_VERSION)
>          return -EINVAL;
> @@ -324,12 +336,16 @@ int cpu_load(QEMUFile *f, void *opaque, int version_id)
>              qemu_get_be64s(f, &env->mtrr_var[i].mask);
>          }
>      }
> +
>      if (version_id >= 9) {
> -        for (i = 0; i < sizeof(env->interrupt_bitmap)/8; i++) {
> -            qemu_get_be64s(f, &env->interrupt_bitmap[i]);
> +        qemu_get_sbe32s(f, &pending_irq);
> +        memset(&env->interrupt_bitmap, 0, sizeof(env->interrupt_bitmap));
> +        if (pending_irq >= 0) {
> +            env->interrupt_bitmap[pending_irq / 64] |=
> +                (uint64_t)1 << (pending_irq % 64);
>          }
> -        qemu_get_be64s(f, &env->tsc);
>          qemu_get_be32s(f, &env->mp_state);
> +        qemu_get_be64s(f, &env->tsc);
>      }
>  
>      /* XXX: ensure compatiblity for halted bit ? */
>
>   

[Qemu-devel] Re: [PATCH] KVM: x86: Refactor persistent CPU state

[Jan Kiszka]

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Anthony Liguori wrote:
> Jan Kiszka wrote:
>> This patch aligns the KVM-related layout and encoding of the CPU state
>> to be saved to disk or migrated with qemu-kvm. The major differences are
>> reordering of fields and a compressed interrupt_bitmap into a single
>> number as there can be no more than one pending IRQ at a time.
>>
>> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
>>   
> 
> We need a version bump, no?

No, we just did you recently when merging my old version of this
refactoring. Both qemu and qemu-kvm will be on number 9 after this.

Jan


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