linux-kernel - [PATCH v2 7/7] Drivers: hv: Use "entry virt" APIs to do work before returning to lower VTL

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Message-ID: <20250828000156.23389-8-seanjc@google.com>
Date: Wed, 27 Aug 2025 17:01:56 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Marc Zyngier <maz@...nel.org>, Oliver Upton <oliver.upton@...ux.dev>, 
	Catalin Marinas <catalin.marinas@....com>, Will Deacon <will@...nel.org>, 
	Tianrui Zhao <zhaotianrui@...ngson.cn>, Bibo Mao <maobibo@...ngson.cn>, 
	Huacai Chen <chenhuacai@...nel.org>, Anup Patel <anup@...infault.org>, 
	Paul Walmsley <paul.walmsley@...ive.com>, Palmer Dabbelt <palmer@...belt.com>, 
	Albert Ou <aou@...s.berkeley.edu>, Sean Christopherson <seanjc@...gle.com>, 
	Paolo Bonzini <pbonzini@...hat.com>, Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, 
	Borislav Petkov <bp@...en8.de>, Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org, 
	"K. Y. Srinivasan" <kys@...rosoft.com>, Haiyang Zhang <haiyangz@...rosoft.com>, Wei Liu <wei.liu@...nel.org>, 
	Dexuan Cui <decui@...rosoft.com>, Peter Zijlstra <peterz@...radead.org>, 
	Andy Lutomirski <luto@...nel.org>, "Paul E. McKenney" <paulmck@...nel.org>, 
	Frederic Weisbecker <frederic@...nel.org>, Neeraj Upadhyay <neeraj.upadhyay@...nel.org>, 
	Joel Fernandes <joelagnelf@...dia.com>, Josh Triplett <josh@...htriplett.org>, 
	Boqun Feng <boqun.feng@...il.com>, Uladzislau Rezki <urezki@...il.com>
Cc: linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
	kvmarm@...ts.linux.dev, kvm@...r.kernel.org, loongarch@...ts.linux.dev, 
	kvm-riscv@...ts.infradead.org, linux-riscv@...ts.infradead.org, 
	linux-hyperv@...r.kernel.org, rcu@...r.kernel.org, 
	Nuno Das Neves <nunodasneves@...ux.microsoft.com>, Mukesh R <mrathor@...ux.microsoft.com>
Subject: [PATCH v2 7/7] Drivers: hv: Use "entry virt" APIs to do work before
 returning to lower VTL

Use the kernel's common "entry virt" APIs to handle pending work prior to
returning to a lower VTL.  Drop the now-defunct common MSHV helper for
doing work as the VTL driver was the last user.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 drivers/hv/Kconfig         |  1 +
 drivers/hv/mshv.h          |  2 --
 drivers/hv/mshv_common.c   | 22 ----------------------
 drivers/hv/mshv_vtl_main.c | 11 +++--------
 4 files changed, 4 insertions(+), 32 deletions(-)

diff --git a/drivers/hv/Kconfig b/drivers/hv/Kconfig
index 894037afcbf9..b00b2b3fe3db 100644
--- a/drivers/hv/Kconfig
+++ b/drivers/hv/Kconfig
@@ -85,6 +85,7 @@ config MSHV_VTL
 	# Therefore, do not attempt to access or modify MTRRs here.
 	depends on !MTRR
 	select CPUMASK_OFFSTACK
+	select VIRT_XFER_TO_GUEST_WORK
 	default n
 	help
 	  Select this option to enable Hyper-V VTL driver support.
diff --git a/drivers/hv/mshv.h b/drivers/hv/mshv.h
index 0340a67acd0a..d4813df92b9c 100644
--- a/drivers/hv/mshv.h
+++ b/drivers/hv/mshv.h
@@ -25,6 +25,4 @@ int hv_call_set_vp_registers(u32 vp_index, u64 partition_id, u16 count,
 int hv_call_get_partition_property(u64 partition_id, u64 property_code,
 				   u64 *property_value);
 
-int mshv_do_pre_guest_mode_work(ulong th_flags);
-
 #endif /* _MSHV_H */
diff --git a/drivers/hv/mshv_common.c b/drivers/hv/mshv_common.c
index eb3df3e296bb..aa2be51979fd 100644
--- a/drivers/hv/mshv_common.c
+++ b/drivers/hv/mshv_common.c
@@ -138,25 +138,3 @@ int hv_call_get_partition_property(u64 partition_id,
 	return 0;
 }
 EXPORT_SYMBOL_GPL(hv_call_get_partition_property);
-
-/*
- * Handle any pre-processing before going into the guest mode on this cpu, most
- * notably call schedule(). Must be invoked with both preemption and
- * interrupts enabled.
- *
- * Returns: 0 on success, -errno on error.
- */
-int mshv_do_pre_guest_mode_work(ulong th_flags)
-{
-	if (th_flags & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL))
-		return -EINTR;
-
-	if (th_flags & (_TIF_NEED_RESCHED | _TIF_NEED_RESCHED_LAZY))
-		schedule();
-
-	if (th_flags & _TIF_NOTIFY_RESUME)
-		resume_user_mode_work(NULL);
-
-	return 0;
-}
-EXPORT_SYMBOL_GPL(mshv_do_pre_guest_mode_work);
diff --git a/drivers/hv/mshv_vtl_main.c b/drivers/hv/mshv_vtl_main.c
index 4ca13c54c0a0..1eabed16aab9 100644
--- a/drivers/hv/mshv_vtl_main.c
+++ b/drivers/hv/mshv_vtl_main.c
@@ -8,6 +8,7 @@
  *   Naman Jain <namjain@...ux.microsoft.com>
  */
 
+#include <linux/entry-virt.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/miscdevice.h>
@@ -727,22 +728,16 @@ static int mshv_vtl_ioctl_return_to_lower_vtl(void)
 {
 	preempt_disable();
 	for (;;) {
-		const unsigned long VTL0_WORK = _TIF_SIGPENDING | _TIF_NEED_RESCHED |
-						_TIF_NOTIFY_RESUME | _TIF_NOTIFY_SIGNAL |
-						_TIF_NEED_RESCHED_LAZY;
-		unsigned long ti_work;
 		unsigned long irq_flags;
 		struct hv_vp_assist_page *hvp;
 		int ret;
 
-		ti_work = READ_ONCE(current_thread_info()->flags);
-		if (unlikely(ti_work & VTL0_WORK)) {
+		if (__xfer_to_guest_mode_work_pending()) {
 			preempt_enable();
-			ret = mshv_do_pre_guest_mode_work(ti_work);
+			ret = xfer_to_guest_mode_handle_work();
 			if (ret)
 				return ret;
 			preempt_disable();
-			continue;
 		}
 
 		local_irq_save(irq_flags);
-- 
2.51.0.268.g9569e192d0-goog