diff mbox series

[V5,2/8] x86/hyperv: Set Virtual Trust Level in VMBus init message

Message ID 20230810160412.820246-3-ltykernel@gmail.com
State New
Headers
Series x86/hyperv: Add AMD sev-snp enlightened guest support on hyperv |

Commit Message

Tianyu Lan Aug. 10, 2023, 4:04 p.m. UTC 
  From: Tianyu Lan <tiala@microsoft.com>

SEV-SNP guests on Hyper-V can run at multiple Virtual Trust
Levels (VTL).  During boot, get the VTL at which we're running
using the GET_VP_REGISTERs hypercall, and save the value
for future use.  Then during VMBus initialization, set the VTL
with the saved value as required in the VMBus init message.

Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Signed-off-by: Tianyu Lan <tiala@microsoft.com>
---
* Change since v3:
       Call get_vtl() when SEV-SNP is available and set vtl to 0
       by default if fail to get VTL from Hyper-V.
* Change since v2:
       Update the change log.
---
 arch/x86/hyperv/hv_init.c          | 39 ++++++++++++++++++++++++++++++
 arch/x86/include/asm/hyperv-tlfs.h |  7 ++++++
 drivers/hv/connection.c            |  1 +
 include/asm-generic/mshyperv.h     |  1 +
 include/linux/hyperv.h             |  4 +--
 5 files changed, 50 insertions(+), 2 deletions(-)

Comments

Dexuan Cui Aug. 10, 2023, 10:59 p.m. UTC | #1 
> From: Tianyu Lan <ltykernel@gmail.com>
> Sent: Thursday, August 10, 2023 9:04 AM
>  [...]
> diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
> @@ -378,6 +378,41 @@ static void __init hv_get_partition_id(void)
>  	local_irq_restore(flags);
>  }
> 
> +static u8 __init get_vtl(void)
> +{
> +	u64 control = HV_HYPERCALL_REP_COMP_1 |
> HVCALL_GET_VP_REGISTERS;
> +	struct hv_get_vp_registers_input *input;
> +	struct hv_get_vp_registers_output *output;
> +	unsigned long flags;
> +	u64 ret;

This should be
	u64 ret = 0;

> +	local_irq_save(flags);
> +	input = *this_cpu_ptr(hyperv_pcpu_input_arg);
> +	output = (struct hv_get_vp_registers_output *)input;
> +	if (!input) {
> +		local_irq_restore(flags);
> +		goto done;

Here the uninitialized 'ret' is returned. 

If we move the "done:" label one line earlier, we won't need the 
the above " local_irq_restore(flags);"
Maybe we should add a WARN_ON_ONCE(1) before "goto done"?

> +	}
> +
> +	memset(input, 0, struct_size(input, element, 1));
> +	input->header.partitionid = HV_PARTITION_ID_SELF;
> +	input->header.vpindex = HV_VP_INDEX_SELF;
> +	input->header.inputvtl = 0;
> +	input->element[0].name0 = HV_X64_REGISTER_VSM_VP_STATUS;
> +
> +	ret = hv_do_hypercall(control, input, output);
> +	if (hv_result_success(ret)) {
> +		ret = output->as64.low & HV_X64_VTL_MASK;
> +	} else {
> +		pr_err("Failed to get VTL and set VTL to zero by default.\n");
> +		ret = 0;

If we have "u64 ret = 0;", we won't need the "ret = 0;" here, and we
won't need the curly braces.

> +	}
> +
> +	local_irq_restore(flags);
> +done:
> +	return ret;
> +}

After the above minor issues are fixed, feel free to add
Reviewed-by: Dexuan Cui <decui@microsoft.com>
Wei Liu Aug. 11, 2023, 9:15 p.m. UTC | #2 
On Thu, Aug 10, 2023 at 10:59:35PM +0000, Dexuan Cui wrote:
> > From: Tianyu Lan <ltykernel@gmail.com>
> > Sent: Thursday, August 10, 2023 9:04 AM
> >  [...]
> > diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
> > @@ -378,6 +378,41 @@ static void __init hv_get_partition_id(void)
> >  	local_irq_restore(flags);
> >  }
> > 
> > +static u8 __init get_vtl(void)
> > +{
> > +	u64 control = HV_HYPERCALL_REP_COMP_1 |
> > HVCALL_GET_VP_REGISTERS;
> > +	struct hv_get_vp_registers_input *input;
> > +	struct hv_get_vp_registers_output *output;
> > +	unsigned long flags;
> > +	u64 ret;
> 
> This should be
> 	u64 ret = 0;
> 
> > +	local_irq_save(flags);
> > +	input = *this_cpu_ptr(hyperv_pcpu_input_arg);
> > +	output = (struct hv_get_vp_registers_output *)input;
> > +	if (!input) {
> > +		local_irq_restore(flags);
> > +		goto done;
> 
> Here the uninitialized 'ret' is returned. 
> 
> If we move the "done:" label one line earlier, we won't need the 
> the above " local_irq_restore(flags);"
> Maybe we should add a WARN_ON_ONCE(1) before "goto done"?

Out of interest why will input be NULL here?

Thanks,
Wei.
Dexuan Cui Aug. 11, 2023, 10:16 p.m. UTC | #3 
> From: Wei Liu <wei.liu@kernel.org>
> Sent: Friday, August 11, 2023 2:15 PM
> To: Dexuan Cui <decui@microsoft.com>
> > [...]
> > > +	local_irq_save(flags);
> > > +	input = *this_cpu_ptr(hyperv_pcpu_input_arg);
> > > +	output = (struct hv_get_vp_registers_output *)input;
> > > +	if (!input) {
> > > +		local_irq_restore(flags);
> > > +		goto done;
> >
> > Here the uninitialized 'ret' is returned.
> >
> > If we move the "done:" label one line earlier, we won't need the
> > the above " local_irq_restore(flags);"
> > Maybe we should add a WARN_ON_ONCE(1) before "goto done"?
> 
> Out of interest why will input be NULL here?
> 
> Thanks,
> Wei.

I don't think 'input' could be NULL here.
IMO we can use it without checking against NULL.
diff mbox series

Patch

diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
index 6c04b52f139b..0fd0f82c4f07 100644
--- a/arch/x86/hyperv/hv_init.c
+++ b/arch/x86/hyperv/hv_init.c
@@ -378,6 +378,41 @@  static void __init hv_get_partition_id(void)
 	local_irq_restore(flags);
 }
 
+static u8 __init get_vtl(void)
+{
+	u64 control = HV_HYPERCALL_REP_COMP_1 | HVCALL_GET_VP_REGISTERS;
+	struct hv_get_vp_registers_input *input;
+	struct hv_get_vp_registers_output *output;
+	unsigned long flags;
+	u64 ret;
+
+	local_irq_save(flags);
+	input = *this_cpu_ptr(hyperv_pcpu_input_arg);
+	output = (struct hv_get_vp_registers_output *)input;
+	if (!input) {
+		local_irq_restore(flags);
+		goto done;
+	}
+
+	memset(input, 0, struct_size(input, element, 1));
+	input->header.partitionid = HV_PARTITION_ID_SELF;
+	input->header.vpindex = HV_VP_INDEX_SELF;
+	input->header.inputvtl = 0;
+	input->element[0].name0 = HV_X64_REGISTER_VSM_VP_STATUS;
+
+	ret = hv_do_hypercall(control, input, output);
+	if (hv_result_success(ret)) {
+		ret = output->as64.low & HV_X64_VTL_MASK;
+	} else {
+		pr_err("Failed to get VTL and set VTL to zero by default.\n");
+		ret = 0;
+	}
+
+	local_irq_restore(flags);
+done:
+	return ret;
+}
+
 /*
  * This function is to be invoked early in the boot sequence after the
  * hypervisor has been detected.
@@ -506,6 +541,10 @@  void __init hyperv_init(void)
 	/* Query the VMs extended capability once, so that it can be cached. */
 	hv_query_ext_cap(0);
 
+	/* Find the VTL */
+	if (cc_platform_has(CC_ATTR_GUEST_SEV_SNP))
+		ms_hyperv.vtl = get_vtl();
+
 	return;
 
 clean_guest_os_id:
diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h
index cea95dcd27c2..4bf0b315b0ce 100644
--- a/arch/x86/include/asm/hyperv-tlfs.h
+++ b/arch/x86/include/asm/hyperv-tlfs.h
@@ -301,6 +301,13 @@  enum hv_isolation_type {
 #define HV_X64_MSR_TIME_REF_COUNT	HV_REGISTER_TIME_REF_COUNT
 #define HV_X64_MSR_REFERENCE_TSC	HV_REGISTER_REFERENCE_TSC
 
+/*
+ * Registers are only accessible via HVCALL_GET_VP_REGISTERS hvcall and
+ * there is not associated MSR address.
+ */
+#define	HV_X64_REGISTER_VSM_VP_STATUS	0x000D0003
+#define	HV_X64_VTL_MASK			GENMASK(3, 0)
+
 /* Hyper-V memory host visibility */
 enum hv_mem_host_visibility {
 	VMBUS_PAGE_NOT_VISIBLE		= 0,
diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c
index 5978e9dbc286..02b54f85dc60 100644
--- a/drivers/hv/connection.c
+++ b/drivers/hv/connection.c
@@ -98,6 +98,7 @@  int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo, u32 version)
 	 */
 	if (version >= VERSION_WIN10_V5) {
 		msg->msg_sint = VMBUS_MESSAGE_SINT;
+		msg->msg_vtl = ms_hyperv.vtl;
 		vmbus_connection.msg_conn_id = VMBUS_MESSAGE_CONNECTION_ID_4;
 	} else {
 		msg->interrupt_page = virt_to_phys(vmbus_connection.int_page);
diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h
index 580c766958de..efd0d2aedad3 100644
--- a/include/asm-generic/mshyperv.h
+++ b/include/asm-generic/mshyperv.h
@@ -54,6 +54,7 @@  struct ms_hyperv_info {
 		};
 	};
 	u64 shared_gpa_boundary;
+	u8 vtl;
 };
 extern struct ms_hyperv_info ms_hyperv;
 extern bool hv_nested;
diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index bfbc37ce223b..1f2bfec4abde 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -665,8 +665,8 @@  struct vmbus_channel_initiate_contact {
 		u64 interrupt_page;
 		struct {
 			u8	msg_sint;
-			u8	padding1[3];
-			u32	padding2;
+			u8	msg_vtl;
+			u8	reserved[6];
 		};
 	};
 	u64 monitor_page1;