diff mbox

kvm: Query KVM for available memory slots

Message ID 20131122191154.16705.42189.stgit@bling.home
State New
Headers show

Commit Message

Alex Williamson Nov. 22, 2013, 7:12 p.m. UTC
KVM reports the number of available memory slots (KVM_CAP_NR_MEMSLOTS)
using the extension interface.  Both x86 and s390 implement this, ARM
and powerpc do not yet enable it.  Convert the static slots array to
be dynamically allocated, supporting more slots when available.
Default to 32 when KVM_CAP_NR_MEMSLOTS is not implemented.  The
motivation for this change is to support more assigned devices, where
memory mapped PCI MMIO BARs typically take one slot each.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
---
 kvm-all.c |   30 +++++++++++++++++++++---------
 1 file changed, 21 insertions(+), 9 deletions(-)

Comments

Thomas Huth Nov. 25, 2013, 10:16 a.m. UTC | #1
On Fri, 22 Nov 2013 12:12:44 -0700
Alex Williamson <alex.williamson@redhat.com> wrote:

> KVM reports the number of available memory slots (KVM_CAP_NR_MEMSLOTS)
> using the extension interface.  Both x86 and s390 implement this, ARM
> and powerpc do not yet enable it.  Convert the static slots array to
> be dynamically allocated, supporting more slots when available.
> Default to 32 when KVM_CAP_NR_MEMSLOTS is not implemented.  The
> motivation for this change is to support more assigned devices, where
> memory mapped PCI MMIO BARs typically take one slot each.
> 
> Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
> ---
>  kvm-all.c |   30 +++++++++++++++++++++---------
>  1 file changed, 21 insertions(+), 9 deletions(-)
> 
> diff --git a/kvm-all.c b/kvm-all.c
> index 4478969..63c4e9b 100644
> --- a/kvm-all.c
> +++ b/kvm-all.c
> @@ -72,7 +72,8 @@ typedef struct kvm_dirty_log KVMDirtyLog;
> 
>  struct KVMState
>  {
> -    KVMSlot slots[32];
> +    KVMSlot *slots;
> +    int nr_slots;
>      int fd;
>      int vmfd;
>      int coalesced_mmio;
> @@ -125,7 +126,7 @@ static KVMSlot *kvm_alloc_slot(KVMState *s)
>  {
>      int i;
> 
> -    for (i = 0; i < ARRAY_SIZE(s->slots); i++) {
> +    for (i = 0; i < s->nr_slots; i++) {
>          if (s->slots[i].memory_size == 0) {
>              return &s->slots[i];
>          }
> @@ -141,7 +142,7 @@ static KVMSlot *kvm_lookup_matching_slot(KVMState *s,
>  {
>      int i;
> 
> -    for (i = 0; i < ARRAY_SIZE(s->slots); i++) {
> +    for (i = 0; i < s->nr_slots; i++) {
>          KVMSlot *mem = &s->slots[i];
> 
>          if (start_addr == mem->start_addr &&
> @@ -163,7 +164,7 @@ static KVMSlot *kvm_lookup_overlapping_slot(KVMState *s,
>      KVMSlot *found = NULL;
>      int i;
> 
> -    for (i = 0; i < ARRAY_SIZE(s->slots); i++) {
> +    for (i = 0; i < s->nr_slots; i++) {
>          KVMSlot *mem = &s->slots[i];
> 
>          if (mem->memory_size == 0 ||
> @@ -185,7 +186,7 @@ int kvm_physical_memory_addr_from_host(KVMState *s, void *ram,
>  {
>      int i;
> 
> -    for (i = 0; i < ARRAY_SIZE(s->slots); i++) {
> +    for (i = 0; i < s->nr_slots; i++) {
>          KVMSlot *mem = &s->slots[i];
> 
>          if (ram >= mem->ram && ram < mem->ram + mem->memory_size) {
> @@ -357,7 +358,7 @@ static int kvm_set_migration_log(int enable)
> 
>      s->migration_log = enable;
> 
> -    for (i = 0; i < ARRAY_SIZE(s->slots); i++) {
> +    for (i = 0; i < s->nr_slots; i++) {
>          mem = &s->slots[i];
> 
>          if (!mem->memory_size) {
> @@ -1383,9 +1384,6 @@ int kvm_init(void)
>  #ifdef KVM_CAP_SET_GUEST_DEBUG
>      QTAILQ_INIT(&s->kvm_sw_breakpoints);
>  #endif
> -    for (i = 0; i < ARRAY_SIZE(s->slots); i++) {
> -        s->slots[i].slot = i;
> -    }
>      s->vmfd = -1;
>      s->fd = qemu_open("/dev/kvm", O_RDWR);
>      if (s->fd == -1) {
> @@ -1409,6 +1407,19 @@ int kvm_init(void)
>          goto err;
>      }
> 
> +    s->nr_slots = kvm_check_extension(s, KVM_CAP_NR_MEMSLOTS);
> +
> +    /* If unspecified, use the previous default value */

I'd remove the "previous" in the comment here, because if you look at
this code in a couple of years, nobody will remember what "previous" is
refering to here.

> +    if (!s->nr_slots) {
> +        s->nr_slots = 32;
> +    }
> +
> +    s->slots = g_malloc0(s->nr_slots * sizeof(KVMSlot));
> +
> +    for (i = 0; i < s->nr_slots; i++) {
> +        s->slots[i].slot = i;
> +    }
> +
>      /* check the vcpu limits */
>      soft_vcpus_limit = kvm_recommended_vcpus(s);
>      hard_vcpus_limit = kvm_max_vcpus(s);
> @@ -1527,6 +1538,7 @@ err:
>      if (s->fd != -1) {
>          close(s->fd);
>      }
> +    g_free(s->slots);
>      g_free(s);
> 
>      return ret;

Reviewed-by: Thomas Huth <thuth@linux.vnet.ibm.com>
Paolo Bonzini Nov. 25, 2013, 10:41 a.m. UTC | #2
Il 25/11/2013 11:16, Thomas Huth ha scritto:
> On Fri, 22 Nov 2013 12:12:44 -0700
> Alex Williamson <alex.williamson@redhat.com> wrote:
> 
>> KVM reports the number of available memory slots (KVM_CAP_NR_MEMSLOTS)
>> using the extension interface.  Both x86 and s390 implement this, ARM
>> and powerpc do not yet enable it.  Convert the static slots array to
>> be dynamically allocated, supporting more slots when available.
>> Default to 32 when KVM_CAP_NR_MEMSLOTS is not implemented.  The
>> motivation for this change is to support more assigned devices, where
>> memory mapped PCI MMIO BARs typically take one slot each.
>>
>> Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
>> ---
>>  kvm-all.c |   30 +++++++++++++++++++++---------
>>  1 file changed, 21 insertions(+), 9 deletions(-)
>>
>> diff --git a/kvm-all.c b/kvm-all.c
>> index 4478969..63c4e9b 100644
>> --- a/kvm-all.c
>> +++ b/kvm-all.c
>> @@ -72,7 +72,8 @@ typedef struct kvm_dirty_log KVMDirtyLog;
>>
>>  struct KVMState
>>  {
>> -    KVMSlot slots[32];
>> +    KVMSlot *slots;
>> +    int nr_slots;
>>      int fd;
>>      int vmfd;
>>      int coalesced_mmio;
>> @@ -125,7 +126,7 @@ static KVMSlot *kvm_alloc_slot(KVMState *s)
>>  {
>>      int i;
>>
>> -    for (i = 0; i < ARRAY_SIZE(s->slots); i++) {
>> +    for (i = 0; i < s->nr_slots; i++) {
>>          if (s->slots[i].memory_size == 0) {
>>              return &s->slots[i];
>>          }
>> @@ -141,7 +142,7 @@ static KVMSlot *kvm_lookup_matching_slot(KVMState *s,
>>  {
>>      int i;
>>
>> -    for (i = 0; i < ARRAY_SIZE(s->slots); i++) {
>> +    for (i = 0; i < s->nr_slots; i++) {
>>          KVMSlot *mem = &s->slots[i];
>>
>>          if (start_addr == mem->start_addr &&
>> @@ -163,7 +164,7 @@ static KVMSlot *kvm_lookup_overlapping_slot(KVMState *s,
>>      KVMSlot *found = NULL;
>>      int i;
>>
>> -    for (i = 0; i < ARRAY_SIZE(s->slots); i++) {
>> +    for (i = 0; i < s->nr_slots; i++) {
>>          KVMSlot *mem = &s->slots[i];
>>
>>          if (mem->memory_size == 0 ||
>> @@ -185,7 +186,7 @@ int kvm_physical_memory_addr_from_host(KVMState *s, void *ram,
>>  {
>>      int i;
>>
>> -    for (i = 0; i < ARRAY_SIZE(s->slots); i++) {
>> +    for (i = 0; i < s->nr_slots; i++) {
>>          KVMSlot *mem = &s->slots[i];
>>
>>          if (ram >= mem->ram && ram < mem->ram + mem->memory_size) {
>> @@ -357,7 +358,7 @@ static int kvm_set_migration_log(int enable)
>>
>>      s->migration_log = enable;
>>
>> -    for (i = 0; i < ARRAY_SIZE(s->slots); i++) {
>> +    for (i = 0; i < s->nr_slots; i++) {
>>          mem = &s->slots[i];
>>
>>          if (!mem->memory_size) {
>> @@ -1383,9 +1384,6 @@ int kvm_init(void)
>>  #ifdef KVM_CAP_SET_GUEST_DEBUG
>>      QTAILQ_INIT(&s->kvm_sw_breakpoints);
>>  #endif
>> -    for (i = 0; i < ARRAY_SIZE(s->slots); i++) {
>> -        s->slots[i].slot = i;
>> -    }
>>      s->vmfd = -1;
>>      s->fd = qemu_open("/dev/kvm", O_RDWR);
>>      if (s->fd == -1) {
>> @@ -1409,6 +1407,19 @@ int kvm_init(void)
>>          goto err;
>>      }
>>
>> +    s->nr_slots = kvm_check_extension(s, KVM_CAP_NR_MEMSLOTS);
>> +
>> +    /* If unspecified, use the previous default value */
> 
> I'd remove the "previous" in the comment here, because if you look at
> this code in a couple of years, nobody will remember what "previous" is
> refering to here.
> 
>> +    if (!s->nr_slots) {
>> +        s->nr_slots = 32;
>> +    }
>> +
>> +    s->slots = g_malloc0(s->nr_slots * sizeof(KVMSlot));
>> +
>> +    for (i = 0; i < s->nr_slots; i++) {
>> +        s->slots[i].slot = i;
>> +    }
>> +
>>      /* check the vcpu limits */
>>      soft_vcpus_limit = kvm_recommended_vcpus(s);
>>      hard_vcpus_limit = kvm_max_vcpus(s);
>> @@ -1527,6 +1538,7 @@ err:
>>      if (s->fd != -1) {
>>          close(s->fd);
>>      }
>> +    g_free(s->slots);
>>      g_free(s);
>>
>>      return ret;
> 
> Reviewed-by: Thomas Huth <thuth@linux.vnet.ibm.com>

Thanks, applied to uq/master with your suggested change.

Paolo
diff mbox

Patch

diff --git a/kvm-all.c b/kvm-all.c
index 4478969..63c4e9b 100644
--- a/kvm-all.c
+++ b/kvm-all.c
@@ -72,7 +72,8 @@  typedef struct kvm_dirty_log KVMDirtyLog;
 
 struct KVMState
 {
-    KVMSlot slots[32];
+    KVMSlot *slots;
+    int nr_slots;
     int fd;
     int vmfd;
     int coalesced_mmio;
@@ -125,7 +126,7 @@  static KVMSlot *kvm_alloc_slot(KVMState *s)
 {
     int i;
 
-    for (i = 0; i < ARRAY_SIZE(s->slots); i++) {
+    for (i = 0; i < s->nr_slots; i++) {
         if (s->slots[i].memory_size == 0) {
             return &s->slots[i];
         }
@@ -141,7 +142,7 @@  static KVMSlot *kvm_lookup_matching_slot(KVMState *s,
 {
     int i;
 
-    for (i = 0; i < ARRAY_SIZE(s->slots); i++) {
+    for (i = 0; i < s->nr_slots; i++) {
         KVMSlot *mem = &s->slots[i];
 
         if (start_addr == mem->start_addr &&
@@ -163,7 +164,7 @@  static KVMSlot *kvm_lookup_overlapping_slot(KVMState *s,
     KVMSlot *found = NULL;
     int i;
 
-    for (i = 0; i < ARRAY_SIZE(s->slots); i++) {
+    for (i = 0; i < s->nr_slots; i++) {
         KVMSlot *mem = &s->slots[i];
 
         if (mem->memory_size == 0 ||
@@ -185,7 +186,7 @@  int kvm_physical_memory_addr_from_host(KVMState *s, void *ram,
 {
     int i;
 
-    for (i = 0; i < ARRAY_SIZE(s->slots); i++) {
+    for (i = 0; i < s->nr_slots; i++) {
         KVMSlot *mem = &s->slots[i];
 
         if (ram >= mem->ram && ram < mem->ram + mem->memory_size) {
@@ -357,7 +358,7 @@  static int kvm_set_migration_log(int enable)
 
     s->migration_log = enable;
 
-    for (i = 0; i < ARRAY_SIZE(s->slots); i++) {
+    for (i = 0; i < s->nr_slots; i++) {
         mem = &s->slots[i];
 
         if (!mem->memory_size) {
@@ -1383,9 +1384,6 @@  int kvm_init(void)
 #ifdef KVM_CAP_SET_GUEST_DEBUG
     QTAILQ_INIT(&s->kvm_sw_breakpoints);
 #endif
-    for (i = 0; i < ARRAY_SIZE(s->slots); i++) {
-        s->slots[i].slot = i;
-    }
     s->vmfd = -1;
     s->fd = qemu_open("/dev/kvm", O_RDWR);
     if (s->fd == -1) {
@@ -1409,6 +1407,19 @@  int kvm_init(void)
         goto err;
     }
 
+    s->nr_slots = kvm_check_extension(s, KVM_CAP_NR_MEMSLOTS);
+
+    /* If unspecified, use the previous default value */
+    if (!s->nr_slots) {
+        s->nr_slots = 32;
+    }
+
+    s->slots = g_malloc0(s->nr_slots * sizeof(KVMSlot));
+
+    for (i = 0; i < s->nr_slots; i++) {
+        s->slots[i].slot = i;
+    }
+
     /* check the vcpu limits */
     soft_vcpus_limit = kvm_recommended_vcpus(s);
     hard_vcpus_limit = kvm_max_vcpus(s);
@@ -1527,6 +1538,7 @@  err:
     if (s->fd != -1) {
         close(s->fd);
     }
+    g_free(s->slots);
     g_free(s);
 
     return ret;