Re: [PATCH v5 06/65] kvm: Introduce support for memory_attributes

[Wang, Lei]

On 2/29/2024 14:36, Xiaoyao Li wrote:> Introduce the helper functions to set 
the attributes of a range of
> memory to private or shared.
> 
> This is necessary to notify KVM the private/shared attribute of each gpa
> range. KVM needs the information to decide the GPA needs to be mapped at
> hva-based shared memory or guest_memfd based private memory.
> 
> Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
> ---
> Changes in v4:
> - move the check of kvm_supported_memory_attributes to the common
>   kvm_set_memory_attributes(); (Wang Wei)
> - change warn_report() to error_report() in kvm_set_memory_attributes()
>   and drop the __func__; (Daniel)
> ---
>  accel/kvm/kvm-all.c  | 44 ++++++++++++++++++++++++++++++++++++++++++++
>  include/sysemu/kvm.h |  3 +++
>  2 files changed, 47 insertions(+)
> 
> diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
> index cd0aa7545a1f..70d482a2c936 100644
> --- a/accel/kvm/kvm-all.c
> +++ b/accel/kvm/kvm-all.c
> @@ -92,6 +92,7 @@ static bool kvm_has_guest_debug;
>  static int kvm_sstep_flags;
>  static bool kvm_immediate_exit;
>  static bool kvm_guest_memfd_supported;
> +static uint64_t kvm_supported_memory_attributes;
>  static hwaddr kvm_max_slot_size = ~0;
>  
>  static const KVMCapabilityInfo kvm_required_capabilites[] = {
> @@ -1304,6 +1305,46 @@ void kvm_set_max_memslot_size(hwaddr max_slot_size)
>      kvm_max_slot_size = max_slot_size;
>  }
>  
> +static int kvm_set_memory_attributes(hwaddr start, hwaddr size, uint64_t 
> attr)
> +{
> +    struct kvm_memory_attributes attrs;
> +    int r;
> +
> +    if (kvm_supported_memory_attributes == 0) {
> +        error_report("No memory attribute supported by KVM\n");
> +        return -EINVAL;
> +    }
> +
> +    if ((attr & kvm_supported_memory_attributes) != attr) {
> +        error_report("memory attribute 0x%lx not supported by KVM,"
> +                     " supported bits are 0x%lx\n",
> +                     attr, kvm_supported_memory_attributes);
> +        return -EINVAL;
> +    }
> +
> +    attrs.attributes = attr;
> +    attrs.address = start;
> +    attrs.size = size;
> +    attrs.flags = 0;
> +
> +    r = kvm_vm_ioctl(kvm_state, KVM_SET_MEMORY_ATTRIBUTES, &attrs);
> +    if (r) {
> +        error_report("failed to set memory (0x%lx+%#zx) with attr 0x%lx 
> error '%s'",
> +                     start, size, attr, strerror(errno));
> +    }
> +    return r;
> +}
> +
> +int kvm_set_memory_attributes_private(hwaddr start, hwaddr size)
> +{
> +    return kvm_set_memory_attributes(start, size, 
> KVM_MEMORY_ATTRIBUTE_PRIVATE);
> +}
> +
> +int kvm_set_memory_attributes_shared(hwaddr start, hwaddr size)
> +{
> +    return kvm_set_memory_attributes(start, size, 0);
> +}
> +
>  /* Called with KVMMemoryListener.slots_lock held */
>  static void kvm_set_phys_mem(KVMMemoryListener *kml,
>                               MemoryRegionSection *section, bool add)
> @@ -2439,6 +2480,9 @@ static int kvm_init(MachineState *ms)
>  
>      kvm_guest_memfd_supported = kvm_check_extension(s, KVM_CAP_GUEST_MEMFD);
>  
> +    ret = kvm_check_extension(s, KVM_CAP_MEMORY_ATTRIBUTES);
> +    kvm_supported_memory_attributes = ret > 0 ? ret : 0;

kvm_check_extension() only returns non-negative value, so we can just

kvm_supported_memory_attributes = kvm_check_extension(s, 
KVM_CAP_MEMORY_ATTRIBUTES);

> +
>      if (object_property_find(OBJECT(current_machine), "kvm-type")) {
>          g_autofree char *kvm_type = 
> object_property_get_str(OBJECT(current_machine),
>                                                              "kvm-type",
> diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h
> index 6cdf82de8372..8e83adfbbd19 100644
> --- a/include/sysemu/kvm.h
> +++ b/include/sysemu/kvm.h
> @@ -546,4 +546,7 @@ uint32_t kvm_dirty_ring_size(void);
>  bool kvm_hwpoisoned_mem(void);
>  
>  int kvm_create_guest_memfd(uint64_t size, uint64_t flags, Error **errp);
> +
> +int kvm_set_memory_attributes_private(hwaddr start, hwaddr size);
> +int kvm_set_memory_attributes_shared(hwaddr start, hwaddr size);
>  #endif