linux-kernel - [PATCH v2 0/7] Drivers: hv: Fix NEED_RESCHED

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Message-ID: <20250828000156.23389-1-seanjc@google.com>
Date: Wed, 27 Aug 2025 17:01:49 -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 0/7] Drivers: hv: Fix NEED_RESCHED_LAZY and use common APIs

Fix a bug where MSHV root partitions (and upper-level VTL code) don't honor
NEED_RESCHED_LAZY, and then deduplicate the TIF related MSHV code by turning
the "kvm" entry APIs into more generic "virt" APIs.

This version is based on

  git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux.git hyperv-next

in order to pickup the VTL changes that are queued for 6.18.  I also
squashed the NEED_RESCHED_LAZY fixes for root and VTL modes into a single
patch, as it should be easy/straightforward to drop the VTL change as needed
if we want this in 6.17 or earlier.

That effectively means the full series is dependent on the VTL changes being
fully merged for 6.18.  But I think that's ok as it's really only the MSHV
changes that have any urgency whatsoever, and I assume that Microsoft is
the only user that truly cares about the MSHV root fix.  I.e. if the whole
thing gets delayed, I think it's only the Hyper-V folks that are impacted.

I have no preference what tree this goes through, or when, and can respin
and/or split as needed.

As with v1, the Hyper-V stuff and non-x86 architectures are compile-tested
only.

v2:
 - Rebase on hyperv-next.
 - Fix and converge the VTL code as well. [Peter, Nuno]

v1: https://lore.kernel.org/all/20250825200622.3759571-1-seanjc@google.com


Sean Christopherson (7):
  Drivers: hv: Handle NEED_RESCHED_LAZY before transferring to guest
  Drivers: hv: Disentangle VTL return cancellation from SIGPENDING
  Drivers: hv: Disable IRQs only after handling pending work before VTL
    return
  entry/kvm: KVM: Move KVM details related to signal/-EINTR into KVM
    proper
  entry: Rename "kvm" entry code assets to "virt" to genericize APIs
  Drivers: hv: Use common "entry virt" APIs to do work in root before
    running guest
  Drivers: hv: Use "entry virt" APIs to do work before returning to
    lower VTL

 MAINTAINERS                                 |  2 +-
 arch/arm64/kvm/Kconfig                      |  2 +-
 arch/arm64/kvm/arm.c                        |  3 +-
 arch/loongarch/kvm/Kconfig                  |  2 +-
 arch/loongarch/kvm/vcpu.c                   |  3 +-
 arch/riscv/kvm/Kconfig                      |  2 +-
 arch/riscv/kvm/vcpu.c                       |  3 +-
 arch/x86/kvm/Kconfig                        |  2 +-
 arch/x86/kvm/vmx/vmx.c                      |  1 -
 arch/x86/kvm/x86.c                          |  3 +-
 drivers/hv/Kconfig                          |  2 ++
 drivers/hv/mshv.h                           |  2 --
 drivers/hv/mshv_common.c                    | 22 ---------------
 drivers/hv/mshv_root_main.c                 | 31 ++++-----------------
 drivers/hv/mshv_vtl_main.c                  | 23 +++++++--------
 include/linux/{entry-kvm.h => entry-virt.h} | 19 +++++--------
 include/linux/kvm_host.h                    | 17 +++++++++--
 include/linux/rcupdate.h                    |  2 +-
 kernel/entry/Makefile                       |  2 +-
 kernel/entry/{kvm.c => virt.c}              | 15 ++++------
 kernel/rcu/tree.c                           |  6 ++--
 virt/kvm/Kconfig                            |  2 +-
 22 files changed, 60 insertions(+), 106 deletions(-)
 rename include/linux/{entry-kvm.h => entry-virt.h} (83%)
 rename kernel/entry/{kvm.c => virt.c} (66%)


base-commit: 03ac62a578566730ab3c320f289f7320798ee2e1
-- 
2.51.0.268.g9569e192d0-goog