From: Sean Christopherson <seanjc@google.com>
To: Marc Zyngier <maz@kernel.org>,
Oliver Upton <oliver.upton@linux.dev>,
Tianrui Zhao <zhaotianrui@loongson.cn>,
Bibo Mao <maobibo@loongson.cn>,
Huacai Chen <chenhuacai@kernel.org>,
Michael Ellerman <mpe@ellerman.id.au>,
Anup Patel <anup@brainfault.org>,
Paul Walmsley <paul.walmsley@sifive.com>,
Palmer Dabbelt <palmer@dabbelt.com>,
Albert Ou <aou@eecs.berkeley.edu>,
Christian Borntraeger <borntraeger@linux.ibm.com>,
Janosch Frank <frankja@linux.ibm.com>,
Claudio Imbrenda <imbrenda@linux.ibm.com>,
Sean Christopherson <seanjc@google.com>,
Paolo Bonzini <pbonzini@redhat.com>
Cc: linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev,
kvm@vger.kernel.org, loongarch@lists.linux.dev,
linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: [PATCH 0/4] KVM: Fold kvm_arch_sched_in() into kvm_arch_vcpu_load()
Date: Tue, 30 Apr 2024 12:31:53 -0700 [thread overview]
Message-ID: <20240430193157.419425-1-seanjc@google.com> (raw)
Drop kvm_arch_sched_in() and instead pass a @sched_in boolean to
kvm_arch_vcpu_load().
While fiddling with an idea for optimizing state management on AMD CPUs,
I wanted to skip re-saving certain host state when a vCPU is scheduled back
in, as the state (theoretically) shouldn't change for the task while it's
scheduled out. Actually doing that was annoying and unnecessarily brittle
due to having a separate API for the kvm_sched_in() case (the state save
needed to be in kvm_arch_vcpu_load() for the common path).
E.g. I could have set a "temporary"-ish flag somewhere in kvm_vcpu, but (a)
that's gross and (b) it would rely on the arbitrary ordering between
sched_in() and vcpu_load() staying the same.
The only real downside I see is that arm64 and riscv end up having to pass
"false" for their direct usage of kvm_arch_vcpu_load(), and passing boolean
literals isn't ideal. But that can be solved by adding an inner helper that
omits the @sched_in param (I almost added a patch to do that, but I couldn't
convince myself it was necessary).
The other motivation for this is to avoid yet another arch hook, and more
arbitrary ordering, if there's a future need to hook kvm_sched_out() (we've
come close on the x86 side several times).
Sean Christopherson (4):
KVM: Plumb in a @sched_in flag to kvm_arch_vcpu_load()
KVM: VMX: Move PLE grow/shrink helpers above vmx_vcpu_load()
KVM: x86: Fold kvm_arch_sched_in() into kvm_arch_vcpu_load()
KVM: Delete the now unused kvm_arch_sched_in()
arch/arm64/include/asm/kvm_host.h | 1 -
arch/arm64/kvm/arm.c | 2 +-
arch/arm64/kvm/emulate-nested.c | 4 +-
arch/arm64/kvm/reset.c | 2 +-
arch/loongarch/include/asm/kvm_host.h | 1 -
arch/loongarch/kvm/vcpu.c | 2 +-
arch/mips/include/asm/kvm_host.h | 1 -
arch/mips/kvm/mmu.c | 2 +-
arch/powerpc/include/asm/kvm_host.h | 1 -
arch/powerpc/kvm/powerpc.c | 2 +-
arch/riscv/include/asm/kvm_host.h | 1 -
arch/riscv/kvm/vcpu.c | 4 +-
arch/s390/include/asm/kvm_host.h | 1 -
arch/s390/kvm/kvm-s390.c | 2 +-
arch/x86/include/asm/kvm-x86-ops.h | 1 -
arch/x86/include/asm/kvm_host.h | 4 +-
arch/x86/kvm/pmu.c | 6 +--
arch/x86/kvm/svm/svm.c | 13 ++---
arch/x86/kvm/vmx/main.c | 2 -
arch/x86/kvm/vmx/vmx.c | 75 +++++++++++++--------------
arch/x86/kvm/vmx/x86_ops.h | 3 +-
arch/x86/kvm/x86.c | 26 +++++-----
include/linux/kvm_host.h | 4 +-
virt/kvm/kvm_main.c | 5 +-
24 files changed, 70 insertions(+), 95 deletions(-)
base-commit: a96cb3bf390eebfead5fc7a2092f8452a7997d1b
--
2.45.0.rc0.197.gbae5840b3b-goog
next reply other threads:[~2024-04-30 19:32 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-30 19:31 Sean Christopherson [this message]
2024-04-30 19:31 ` [PATCH 1/4] KVM: Plumb in a @sched_in flag to kvm_arch_vcpu_load() Sean Christopherson
2024-04-30 19:31 ` [PATCH 2/4] KVM: VMX: Move PLE grow/shrink helpers above vmx_vcpu_load() Sean Christopherson
2024-04-30 19:31 ` [PATCH 3/4] KVM: x86: Fold kvm_arch_sched_in() into kvm_arch_vcpu_load() Sean Christopherson
2024-04-30 19:31 ` [PATCH 4/4] KVM: Delete the now unused kvm_arch_sched_in() Sean Christopherson
2024-05-01 0:28 ` [PATCH 0/4] KVM: Fold kvm_arch_sched_in() into kvm_arch_vcpu_load() Oliver Upton
2024-05-01 14:28 ` Sean Christopherson
2024-05-01 18:01 ` Oliver Upton
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