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

[Xiaoyao Li <xiaoyao.li@xxxxxxxxx>]

On 3/19/2024 10:03 AM, Wang, Lei wrote:
> 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@xxxxxxxxx>
> > ---
> > 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);

Good catch, I will update it in next version.

> > +
> >       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