[RFC PATCH V4 2/4] drivers/hv: Allow vmbus message synic interrupt injected from Hyper-V

From: Tianyu Lan
Date: Sat Jul 26 2025 - 09:43:28 EST


From: Tianyu Lan <tiala@xxxxxxxxxxxxx>

When Secure AVIC is enabled, VMBus driver should
call x2apic Secure AVIC interface to allow Hyper-V
to inject VMBus message interrupt.

Signed-off-by: Tianyu Lan <tiala@xxxxxxxxxxxxx>
---
Change since RFC V3:
- Disable VMBus Message interrupt via hv_enable_
coco_interrupt() in the hv_synic_disable_regs().
---
arch/x86/hyperv/hv_apic.c | 5 +++++
drivers/hv/hv.c | 2 ++
drivers/hv/hv_common.c | 5 +++++
include/asm-generic/mshyperv.h | 1 +
4 files changed, 13 insertions(+)

diff --git a/arch/x86/hyperv/hv_apic.c b/arch/x86/hyperv/hv_apic.c
index e669053b637d..a8de503def37 100644
--- a/arch/x86/hyperv/hv_apic.c
+++ b/arch/x86/hyperv/hv_apic.c
@@ -53,6 +53,11 @@ static void hv_apic_icr_write(u32 low, u32 id)
wrmsrq(HV_X64_MSR_ICR, reg_val);
}

+void hv_enable_coco_interrupt(unsigned int cpu, unsigned int vector, bool set)
+{
+ apic_update_vector(cpu, vector, set);
+}
+
static u32 hv_apic_read(u32 reg)
{
u32 reg_val, hi;
diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c
index 308c8f279df8..aa384dbf38ac 100644
--- a/drivers/hv/hv.c
+++ b/drivers/hv/hv.c
@@ -310,6 +310,7 @@ void hv_synic_enable_regs(unsigned int cpu)
if (vmbus_irq != -1)
enable_percpu_irq(vmbus_irq, 0);
shared_sint.as_uint64 = hv_get_msr(HV_MSR_SINT0 + VMBUS_MESSAGE_SINT);
+ hv_enable_coco_interrupt(cpu, vmbus_interrupt, true);

shared_sint.vector = vmbus_interrupt;
shared_sint.masked = false;
@@ -342,6 +343,7 @@ void hv_synic_disable_regs(unsigned int cpu)
union hv_synic_scontrol sctrl;

shared_sint.as_uint64 = hv_get_msr(HV_MSR_SINT0 + VMBUS_MESSAGE_SINT);
+ hv_enable_coco_interrupt(cpu, vmbus_interrupt, false);

shared_sint.masked = 1;

diff --git a/drivers/hv/hv_common.c b/drivers/hv/hv_common.c
index 49898d10faff..0f024ab3d360 100644
--- a/drivers/hv/hv_common.c
+++ b/drivers/hv/hv_common.c
@@ -716,6 +716,11 @@ u64 __weak hv_tdx_hypercall(u64 control, u64 param1, u64 param2)
}
EXPORT_SYMBOL_GPL(hv_tdx_hypercall);

+void __weak hv_enable_coco_interrupt(unsigned int cpu, unsigned int vector, bool set)
+{
+}
+EXPORT_SYMBOL_GPL(hv_enable_coco_interrupt);
+
void hv_identify_partition_type(void)
{
/* Assume guest role */
diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h
index a729b77983fa..7907c9878369 100644
--- a/include/asm-generic/mshyperv.h
+++ b/include/asm-generic/mshyperv.h
@@ -333,6 +333,7 @@ bool hv_is_isolation_supported(void);
bool hv_isolation_type_snp(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 hv_enable_coco_interrupt(unsigned int cpu, unsigned int vector, bool set);
void hyperv_cleanup(void);
bool hv_query_ext_cap(u64 cap_query);
void hv_setup_dma_ops(struct device *dev, bool coherent);
--
2.25.1