On 2/5/20 1:02 PM, Thomas Huth wrote:
> On 03/02/2020 14.19, Christian Borntraeger wrote:
>> From: Janosch Frank <frankja@xxxxxxxxxxxxx>
>>
>> Now that we can't access guest memory anymore, we have a dedicated
>> sattelite block that's a bounce buffer for instruction data.
>>
>> We re-use the memop interface to copy the instruction data to / from
>> userspace. This lets us re-use a lot of QEMU code which used that
>> interface to make logical guest memory accesses which are not possible
>> anymore in protected mode anyway.
>>
>> Signed-off-by: Janosch Frank <frankja@xxxxxxxxxxxxx>
>> ---
> [...]
>> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
>> index eab741bc12c3..20969ce12096 100644
>> --- a/include/uapi/linux/kvm.h
>> +++ b/include/uapi/linux/kvm.h
>> @@ -466,7 +466,7 @@ struct kvm_translation {
>> __u8 pad[5];
>> };
>>
>> -/* for KVM_S390_MEM_OP */
>> +/* for KVM_S390_MEM_OP and KVM_S390_SIDA_OP */
>> struct kvm_s390_mem_op {
>> /* in */
>> __u64 gaddr; /* the guest address */
>> @@ -475,11 +475,17 @@ struct kvm_s390_mem_op {
>> __u32 op; /* type of operation */
>> __u64 buf; /* buffer in userspace */
>> __u8 ar; /* the access register number */
>> - __u8 reserved[31]; /* should be set to 0 */
>> + __u8 reserved21[3]; /* should be set to 0 */
>> + __u32 offset; /* offset into the sida */
>> + __u8 reserved28[24]; /* should be set to 0 */
>> };
>> +
>> +
>> /* types for kvm_s390_mem_op->op */
>> #define KVM_S390_MEMOP_LOGICAL_READ 0
>> #define KVM_S390_MEMOP_LOGICAL_WRITE 1
>> +#define KVM_S390_MEMOP_SIDA_READ 2
>> +#define KVM_S390_MEMOP_SIDA_WRITE 3
>> /* flags for kvm_s390_mem_op->flags */
>> #define KVM_S390_MEMOP_F_CHECK_ONLY (1ULL << 0)
>> #define KVM_S390_MEMOP_F_INJECT_EXCEPTION (1ULL << 1)
>> @@ -1510,6 +1516,7 @@ struct kvm_pv_cmd {
>> /* Available with KVM_CAP_S390_PROTECTED */
>> #define KVM_S390_PV_COMMAND _IOW(KVMIO, 0xc5, struct kvm_pv_cmd)
>> #define KVM_S390_PV_COMMAND_VCPU _IOW(KVMIO, 0xc6, struct kvm_pv_cmd)
>> +#define KVM_S390_SIDA_OP _IOW(KVMIO, 0xc7, struct kvm_s390_mem_op)
>>
>> /* Secure Encrypted Virtualization command */
>> enum sev_cmd_id {
>>
>
> Uh, why the mix of a new ioctl with the existing mem_op stuff? Could you
> please either properly integrate this into the MEM_OP ioctl (and e.g.
> use gaddr as offset for the new SIDA_READ and SIDA_WRITE subcodes), or
> completely separate it for a new ioctl, i.e. introduce a new struct for
> the new ioctl instead of recycling the struct kvm_s390_mem_op here?
> (and in case you ask me, I'd slightly prefer to integrate everything
> into MEM_OP instead of introducing a new ioctl here).
*cough* David and Christian didn't like the memop solution and it took
me a long time to get this to work properly in QEMU...
I wouldn't mind a dedicated struct.
>
> In any case, please also update Documentation/virt/kvm/api.txt with the
> new SIDA functions.
>
> Thanks,
> Thomas
>
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