Re: [PATCH v3 06/70] kvm: Introduce support for memory_attributes

Xiaoyao Li
2023-11-16T03:40:23Z

On 11/15/2023 6:38 PM, Daniel P. Berrangé wrote:
> On Wed, Nov 15, 2023 at 02:14:15AM -0500, 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>
>> ---
>> accel/kvm/kvm-all.c | 42 ++++++++++++++++++++++++++++++++++++++++++
>> include/sysemu/kvm.h | 3 +++
>> 2 files changed, 45 insertions(+)
>>
>> diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
>> index 69afeb47c9c0..76e2404d54d2 100644
>> --- a/accel/kvm/kvm-all.c
>> +++ b/accel/kvm/kvm-all.c
>> @@ -102,6 +102,7 @@ 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[] = {
>> @@ -1305,6 +1306,44 @@ 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;
>> +
>> + 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) {
>> + warn_report("%s: failed to set memory (0x%lx+%#zx) with attr 0x%lx error '%s'",
>> + __func__, start, size, attr, strerror(errno));
>
> This is an error condition rather than an warning condition.
>
> Also again I think __func__ is generally not required in an error message,
> if the error message text is suitably descriptive - applies to other
> patches in this series too.

Get it.

>> + }
>> + return r;
>> +}
>> +
>> +int kvm_set_memory_attributes_private(hwaddr start, hwaddr size)
>> +{
>> + if (!(kvm_supported_memory_attributes & KVM_MEMORY_ATTRIBUTE_PRIVATE)) {
>> + error_report("KVM doesn't support PRIVATE memory attribute\n");
>> + return -EINVAL;
>> + }
>> +
>> + return kvm_set_memory_attributes(start, size, KVM_MEMORY_ATTRIBUTE_PRIVATE);
>> +}
>> +
>> +int kvm_set_memory_attributes_shared(hwaddr start, hwaddr size)
>> +{
>> + if (!(kvm_supported_memory_attributes & KVM_MEMORY_ATTRIBUTE_PRIVATE)) {
>> + error_report("KVM doesn't support PRIVATE memory attribute\n");
>> + return -EINVAL;
>> + }
>> +
>> + 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)
>> @@ -2440,6 +2479,9 @@ 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;
>> +
>> 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 fedc28c7d17f..0e88958190a4 100644
>> --- a/include/sysemu/kvm.h
>> +++ b/include/sysemu/kvm.h
>> @@ -540,4 +540,7 @@ bool kvm_dirty_ring_enabled(void);
>> uint32_t kvm_dirty_ring_size(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
>> --
>> 2.34.1
>>
>
> With regards,
> Daniel