Re: [PATCH hyperv-next v2 2/4] drivers: hyperv: VMBus protocol version 6.0

[Roman Kisel <romank@linux.microsoft.com>]

On 5/12/2025 2:49 AM, ALOK TIWARI wrote:
> 
> 
> On 12-05-2025 04:37, Roman Kisel wrote:
>> The confidential VMBus is supported starting from the protocol
>> version 6.0 onwards.
>>
>> Update the relevant definitions, provide a function that returns
>> whether VMBus is condifential or not.
> 
> typo condifential -> confidential
> 
>>
>> Signed-off-by: Roman Kisel <romank@linux.microsoft.com>
>> ---
>>   drivers/hv/vmbus_drv.c         | 12 ++++++
>>   include/asm-generic/mshyperv.h |  1 +
>>   include/linux/hyperv.h         | 71 +++++++++++++++++++++++++---------
>>   3 files changed, 65 insertions(+), 19 deletions(-)
>>
>> diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
>> index 1d5c9dcf712e..e431978fa408 100644
>> --- a/drivers/hv/vmbus_drv.c
>> +++ b/drivers/hv/vmbus_drv.c
>> @@ -56,6 +56,18 @@ static long __percpu *vmbus_evt;
>>   int vmbus_irq;
>>   int vmbus_interrupt;
>> +/*
>> + * If the Confidential VMBus is used, the data on the "wire" is not
>> + * visible to either the host or the hypervisor.
>> + */
>> +static bool is_confidential;
>> +
>> +bool vmbus_is_confidential(void)
>> +{
>> +    return is_confidential;
>> +}
>> +EXPORT_SYMBOL_GPL(vmbus_is_confidential);
>> +
>>   /*
>>    * The panic notifier below is responsible solely for unloading the
>>    * vmbus connection, which is necessary in a panic event.
>> diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/ 
>> mshyperv.h
>> index 6c51a25ed7b5..96e0723d0720 100644
>> --- a/include/asm-generic/mshyperv.h
>> +++ b/include/asm-generic/mshyperv.h
>> @@ -377,6 +377,7 @@ static inline int hv_call_create_vp(int node, u64 
>> partition_id, u32 vp_index, u3
>>       return -EOPNOTSUPP;
>>   }
>>   #endif /* CONFIG_MSHV_ROOT */
>> +bool vmbus_is_confidential(void);
>>   #if IS_ENABLED(CONFIG_HYPERV_VTL_MODE)
>>   u8 __init get_vtl(void);
>> diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
>> index 1f310fbbc4f9..3cf48f29e6b4 100644
>> --- a/include/linux/hyperv.h
>> +++ b/include/linux/hyperv.h
>> @@ -265,16 +265,19 @@ static inline u32 hv_get_avail_to_write_percent(
>>    * Linux kernel.
>>    */
>> -#define VERSION_WS2008  ((0 << 16) | (13))
>> -#define VERSION_WIN7    ((1 << 16) | (1))
>> -#define VERSION_WIN8    ((2 << 16) | (4))
>> -#define VERSION_WIN8_1    ((3 << 16) | (0))
>> -#define VERSION_WIN10 ((4 << 16) | (0))
>> -#define VERSION_WIN10_V4_1 ((4 << 16) | (1))
>> -#define VERSION_WIN10_V5 ((5 << 16) | (0))
>> -#define VERSION_WIN10_V5_1 ((5 << 16) | (1))
>> -#define VERSION_WIN10_V5_2 ((5 << 16) | (2))
>> -#define VERSION_WIN10_V5_3 ((5 << 16) | (3))
>> +#define VMBUS_MAKE_VERSION(MAJ, MIN)    ((((u32)MAJ) << 16) | (MIN))
>> +#define VERSION_WS2008                    VMBUS_MAKE_VERSION(0, 13)
>> +#define VERSION_WIN7                    VMBUS_MAKE_VERSION(1, 1)
>> +#define VERSION_WIN8                    VMBUS_MAKE_VERSION(2, 4)
>> +#define VERSION_WIN8_1                    VMBUS_MAKE_VERSION(3, 0)
>> +#define VERSION_WIN10                    VMBUS_MAKE_VERSION(4, 0)
>> +#define VERSION_WIN10_V4_1                VMBUS_MAKE_VERSION(4, 1)
>> +#define VERSION_WIN10_V5                VMBUS_MAKE_VERSION(5, 0)
>> +#define VERSION_WIN10_V5_1                VMBUS_MAKE_VERSION(5, 1)
>> +#define VERSION_WIN10_V5_2                VMBUS_MAKE_VERSION(5, 2)
>> +#define VERSION_WIN10_V5_3                VMBUS_MAKE_VERSION(5, 3)
>> +#define VERSION_WIN_IRON                VERSION_WIN10_V5_3
>> +#define VERSION_WIN_COPPER                VMBUS_MAKE_VERSION(6, 0)
>>   /* Make maximum size of pipe payload of 16K */
>>   #define MAX_PIPE_DATA_PAYLOAD        (sizeof(u8) * 16384)
>> @@ -335,14 +338,22 @@ struct vmbus_channel_offer {
>>   } __packed;
>>   /* Server Flags */
>> -#define VMBUS_CHANNEL_ENUMERATE_DEVICE_INTERFACE    1
>> -#define VMBUS_CHANNEL_SERVER_SUPPORTS_TRANSFER_PAGES    2
>> -#define VMBUS_CHANNEL_SERVER_SUPPORTS_GPADLS        4
>> -#define VMBUS_CHANNEL_NAMED_PIPE_MODE            0x10
>> -#define VMBUS_CHANNEL_LOOPBACK_OFFER            0x100
>> -#define VMBUS_CHANNEL_PARENT_OFFER            0x200
>> -#define VMBUS_CHANNEL_REQUEST_MONITORED_NOTIFICATION    0x400
>> -#define VMBUS_CHANNEL_TLNPI_PROVIDER_OFFER        0x2000
>> +#define VMBUS_CHANNEL_ENUMERATE_DEVICE_INTERFACE        0x0001
>> +/*
>> + * This flag indicates that the channel is offered by the paravisor, 
>> and must
>> + * use encrypted memory for the channel ring buffer.
>> + */
>> +#define VMBUS_CHANNEL_CONFIDENTIAL_RING_BUFFER            0x0002
>> +/*
>> + * This flag indicates that the channel is offered by the paravisor, 
>> and must
>> + * use encrypted memory for GPA direct packets and additional GPADLs.
>> + */
>> +#define VMBUS_CHANNEL_CONFIDENTIAL_EXTERNAL_MEMORY        0x0004
>> +#define VMBUS_CHANNEL_NAMED_PIPE_MODE                    0x0010
>> +#define VMBUS_CHANNEL_LOOPBACK_OFFER                    0x0100
>> +#define VMBUS_CHANNEL_PARENT_OFFER                        0x0200
>> +#define VMBUS_CHANNEL_REQUEST_MONITORED_NOTIFICATION    0x0400
>> +#define VMBUS_CHANNEL_TLNPI_PROVIDER_OFFER                0x2000
>>   struct vmpacket_descriptor {
>>       u16 type;
>> @@ -621,6 +632,12 @@ struct vmbus_channel_relid_released {
>>       u32 child_relid;
>>   } __packed;
>> +/*
>> + * Used by the paravisor only, means that the encrypted ring buffers and
>> + * the encrypted external memory are supported
> 
> Clearly convey the purpose of the flag, similar to the previous one
> For example ->"Indicates support for encrypted ring buffers and external 
> memory, used exclusively by the paravisor."
> 

Will do, appreciate your help!!

>> + */
>> +#define VMBUS_FEATURE_FLAG_CONFIDENTIAL_CHANNELS    0x10
>> +
>>   struct vmbus_channel_initiate_contact {
>>       struct vmbus_channel_message_header header;
>>       u32 vmbus_version_requested;
>> @@ -630,7 +647,8 @@ struct vmbus_channel_initiate_contact {
>>           struct {
>>               u8    msg_sint;
>>               u8    msg_vtl;
>> -            u8    reserved[6];
>> +            u8    reserved[2];
>> +            u32 feature_flags; /* VMBus version 6.0 */
>>           };
>>       };
>>       u64 monitor_page1;
>> @@ -1002,6 +1020,11 @@ struct vmbus_channel {
>>       /* The max size of a packet on this channel */
>>       u32 max_pkt_size;
>> +
>> +    /* The ring buffer is encrypted */
>> +    bool confidential_ring_buffer;
>> +    /* The external memory is encrypted */
>> +    bool confidential_external_memory;
>>   };
> 
> Thanks,
> Alok
> 

-- 
Thank you,
Roman