From: Marc Zyngier <maz@kernel.org>
To: kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org,
linux-arm-kernel@lists.infradead.org
Cc: James Morse <james.morse@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Alexandru Elisei <alexandru.elisei@arm.com>,
Quentin Perret <qperret@google.com>,
Will Deacon <will@kernel.org>,
broonie@kernel.org, kernel-team@android.com
Subject: [PATCH 0/4] KVM: arm64: Stop mapping current thread_info at EL2
Date: Thu, 21 Oct 2021 16:11:20 +0100 [thread overview]
Message-ID: <20211021151124.3098113-1-maz@kernel.org> (raw)
It recently became apparent that we are mapping each vcpu thread's
thread_info structure at EL2 for the sole purpose of checking on the
TIF_FOREIGN_FPSTATE flag.
Given that this looks like a slightly over-engineered way of sharing a
single bit of information, let's move to a slightly more obvious
implementation by maintaining a vcpu-private shadow flag that
represents the same state.
I also take this opportunity to add what looks like a missing, and
nonetheless crucial piece of information to the FPSIMD code regarding
the way KVM (ab)uses the TIF_FOREIGN_FPSTATE.
Lightly tested on an A53 box with a bunch of paranoia instances
running in both host and guests.
Marc Zyngier (4):
KVM: arm64: Reorder vcpu flag definitions
KVM: arm64: Introduce flag shadowing TIF_FOREIGN_FPSTATE
KVM: arm64: Stop mapping current thread_info at EL2
arm64/fpsimd: Document the use of TIF_FOREIGN_FPSTATE by KVM
arch/arm64/include/asm/kvm_host.h | 28 ++++++++++++-------------
arch/arm64/kernel/fpsimd.c | 5 ++++-
arch/arm64/kvm/arm.c | 1 +
arch/arm64/kvm/fpsimd.c | 20 ++++++++----------
arch/arm64/kvm/hyp/include/hyp/switch.h | 3 +--
arch/arm64/kvm/hyp/nvhe/switch.c | 1 -
arch/arm64/kvm/hyp/vhe/switch.c | 1 -
7 files changed, 29 insertions(+), 30 deletions(-)
--
2.30.2
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next reply other threads:[~2021-10-21 15:14 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-21 15:11 Marc Zyngier [this message]
2021-10-21 15:11 ` [PATCH 1/4] KVM: arm64: Reorder vcpu flag definitions Marc Zyngier
2021-10-21 15:11 ` [PATCH 2/4] KVM: arm64: Introduce flag shadowing TIF_FOREIGN_FPSTATE Marc Zyngier
2021-10-21 15:24 ` Mark Brown
2021-10-21 15:11 ` [PATCH 3/4] KVM: arm64: Stop mapping current thread_info at EL2 Marc Zyngier
2021-10-21 15:11 ` [PATCH 4/4] arm64/fpsimd: Document the use of TIF_FOREIGN_FPSTATE by KVM Marc Zyngier
2021-10-21 15:57 ` Mark Brown
2021-10-27 11:26 ` Marc Zyngier
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