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Message-ID: <20250828010557.123869-3-romank@linux.microsoft.com>
Date: Wed, 27 Aug 2025 18:05:43 -0700
From: Roman Kisel <romank@...ux.microsoft.com>
To: arnd@...db.de,
bp@...en8.de,
corbet@....net,
dave.hansen@...ux.intel.com,
decui@...rosoft.com,
haiyangz@...rosoft.com,
hpa@...or.com,
kys@...rosoft.com,
mikelley@...rosoft.com,
mingo@...hat.com,
tglx@...utronix.de,
Tianyu.Lan@...rosoft.com,
wei.liu@...nel.org,
x86@...nel.org,
linux-hyperv@...r.kernel.org,
linux-doc@...r.kernel.org,
linux-kernel@...r.kernel.org,
linux-arch@...r.kernel.org
Cc: benhill@...rosoft.com,
bperkins@...rosoft.com,
sunilmut@...rosoft.com,
romank@...ux.microsoft.com
Subject: [PATCH hyperv-next v5 02/16] drivers: hv: VMBus protocol version 6.0
The confidential VMBus is supported starting from the protocol
version 6.0 onwards.
Update the relevant definitions, provide the x86-specific way to
detect availability of the Confidential VMBus and provide a
function that returns whether VMBus is confidential or not.
No functional changes.
Signed-off-by: Roman Kisel <romank@...ux.microsoft.com>
Reviewed-by: Alok Tiwari <alok.a.tiwari@...cle.com>
Reviewed-by: Michael Kelley <mhklinux@...look.com>
---
arch/x86/kernel/cpu/mshyperv.c | 19 ++++++++++
drivers/hv/hv_common.c | 6 +++
drivers/hv/hyperv_vmbus.h | 2 +
drivers/hv/vmbus_drv.c | 12 ++++++
include/asm-generic/mshyperv.h | 1 +
include/hyperv/hvgdk_mini.h | 1 +
include/linux/hyperv.h | 69 ++++++++++++++++++++++++----------
7 files changed, 91 insertions(+), 19 deletions(-)
diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index 25773af116bc..95cd78004b11 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -90,6 +90,25 @@ void hv_set_non_nested_msr(unsigned int reg, u64 value)
}
EXPORT_SYMBOL_GPL(hv_set_non_nested_msr);
+/*
+ * Detect if the confidential VMBus is available.
+ */
+bool hv_confidential_vmbus_available(void)
+{
+ u32 eax;
+
+ eax = cpuid_eax(HYPERV_CPUID_VIRT_STACK_INTERFACE);
+ if (eax != HYPERV_VS_INTERFACE_EAX_SIGNATURE)
+ return false;
+
+ eax = cpuid_eax(HYPERV_CPUID_VIRT_STACK_PROPERTIES);
+
+ /*
+ * The paravisor may set the bit in the hardware confidential VMs.
+ */
+ return eax & HYPERV_VS_PROPERTIES_EAX_CONFIDENTIAL_VMBUS_AVAILABLE;
+}
+
u64 hv_get_msr(unsigned int reg)
{
if (hv_nested)
diff --git a/drivers/hv/hv_common.c b/drivers/hv/hv_common.c
index 8836cf9fad40..fae63c54e531 100644
--- a/drivers/hv/hv_common.c
+++ b/drivers/hv/hv_common.c
@@ -716,6 +716,12 @@ u64 __weak hv_tdx_hypercall(u64 control, u64 param1, u64 param2)
}
EXPORT_SYMBOL_GPL(hv_tdx_hypercall);
+bool __weak hv_confidential_vmbus_available(void)
+{
+ return false;
+}
+EXPORT_SYMBOL_GPL(hv_confidential_vmbus_available);
+
void hv_identify_partition_type(void)
{
/* Assume guest role */
diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h
index b61f01fc1960..6e4c3acc1169 100644
--- a/drivers/hv/hyperv_vmbus.h
+++ b/drivers/hv/hyperv_vmbus.h
@@ -334,6 +334,8 @@ extern const struct vmbus_channel_message_table_entry
/* General vmbus interface */
+bool vmbus_is_confidential(void);
+
struct hv_device *vmbus_device_create(const guid_t *type,
const guid_t *instance,
struct vmbus_channel *channel);
diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index a366365f2c49..8d9488c3174d 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -57,6 +57,18 @@ 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 dbd4c2f3aee3..acb017f6c423 100644
--- a/include/asm-generic/mshyperv.h
+++ b/include/asm-generic/mshyperv.h
@@ -332,6 +332,7 @@ bool hv_is_hibernation_supported(void);
enum hv_isolation_type hv_get_isolation_type(void);
bool hv_is_isolation_supported(void);
bool hv_isolation_type_snp(void);
+bool hv_confidential_vmbus_available(void);
u64 hv_ghcb_hypercall(u64 control, void *input, void *output, u32 input_size);
u64 hv_tdx_hypercall(u64 control, u64 param1, u64 param2);
void hyperv_cleanup(void);
diff --git a/include/hyperv/hvgdk_mini.h b/include/hyperv/hvgdk_mini.h
index 79b7324e4ef5..4b189f9d39cb 100644
--- a/include/hyperv/hvgdk_mini.h
+++ b/include/hyperv/hvgdk_mini.h
@@ -260,6 +260,7 @@ union hv_hypervisor_version_info {
#define HYPERV_CPUID_VIRT_STACK_PROPERTIES 0x40000082
/* Support for the extended IOAPIC RTE format */
#define HYPERV_VS_PROPERTIES_EAX_EXTENDED_IOAPIC_RTE BIT(2)
+#define HYPERV_VS_PROPERTIES_EAX_CONFIDENTIAL_VMBUS_AVAILABLE BIT(3)
#define HYPERV_HYPERVISOR_PRESENT_BIT 0x80000000
#define HYPERV_CPUID_MIN 0x40000005
diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index a59c5c3e95fb..a1820fabbfc0 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -265,16 +265,18 @@ 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_WIN10_V6_0 VMBUS_MAKE_VERSION(6, 0)
/* Make maximum size of pipe payload of 16K */
#define MAX_PIPE_DATA_PAYLOAD (sizeof(u8) * 16384)
@@ -335,14 +337,22 @@ 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 +631,12 @@ 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
+ */
+#define VMBUS_FEATURE_FLAG_CONFIDENTIAL_CHANNELS 0x10
+
struct vmbus_channel_initiate_contact {
struct vmbus_channel_message_header header;
u32 vmbus_version_requested;
@@ -630,7 +646,8 @@ 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;
@@ -1008,6 +1025,10 @@ struct vmbus_channel {
/* boolean to control visibility of sysfs for ring buffer */
bool ring_sysfs_visible;
+ /* The ring buffer is encrypted */
+ bool co_ring_buffer;
+ /* The external memory is encrypted */
+ bool co_external_memory;
};
#define lock_requestor(channel, flags) \
@@ -1032,6 +1053,16 @@ u64 vmbus_request_addr_match(struct vmbus_channel *channel, u64 trans_id,
u64 rqst_addr);
u64 vmbus_request_addr(struct vmbus_channel *channel, u64 trans_id);
+static inline bool is_co_ring_buffer(const struct vmbus_channel_offer_channel *o)
+{
+ return !!(o->offer.chn_flags & VMBUS_CHANNEL_CONFIDENTIAL_RING_BUFFER);
+}
+
+static inline bool is_co_external_memory(const struct vmbus_channel_offer_channel *o)
+{
+ return !!(o->offer.chn_flags & VMBUS_CHANNEL_CONFIDENTIAL_EXTERNAL_MEMORY);
+}
+
static inline bool is_hvsock_offer(const struct vmbus_channel_offer_channel *o)
{
return !!(o->offer.chn_flags & VMBUS_CHANNEL_TLNPI_PROVIDER_OFFER);
--
2.43.0
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