Drivers: hv: Move add_interrupt_randomness() to hypervisor callback sysvec

The Hyper-V ISRs, for normal guests and when running in the hypervisor root
patition, are calling add_interrupt_randomness() as a primary source of
entropy. The call is currently in the ISRs as a common place to handle both
x86/x64 and arm64.

On x86/x64, hypervisor interrupts come through a custom sysvec entry, and
do not go through a generic interrupt handler.

On arm64, hypervisor interrupts come through an emulated GICv3. GICv3 uses
the generic handler handle_percpu_devid_irq(), which does not do
add_interrupt_randomness() -- unlike its counterpart
handle_percpu_irq().

But handle_percpu_devid_irq() is now updated to do the
add_interrupt_randomness(). So add_interrupt_randomness() is now needed
only in Hyper-V's x86/x64 custom sysvec path.

Move add_interrupt_randomness() from the Hyper-V ISRs into the Hyper-V
x86/x64 custom sysvec path, matching the existing STIMER0 sysvec path.

With this change, add_interrupt_randomness() is no longer called from any
device drivers, which is appropriate.

Signed-off-by: Michael Kelley <mhklinux@outlook.com>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Acked-by: Wei Liu <wei.liu@kernel.org>
Link: https://patch.msgid.link/20260402202400.1707-3-mhklkml@zohomail.com

1 files changed, 2 insertions, 0 deletions

diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index 9befdc557d9e..a7dfc29d3470 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -161,6 +161,8 @@ DEFINE_IDTENTRY_SYSVEC(sysvec_hyperv_callback)
 	if (vmbus_handler)
 		vmbus_handler();
 
+	add_interrupt_randomness(HYPERVISOR_CALLBACK_VECTOR);
+
 	if (ms_hyperv.hints & HV_DEPRECATING_AEOI_RECOMMENDED)
 		apic_eoi();