All of lore.kernel.org
 help / color / mirror / Atom feed
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


WARNING: multiple messages have this Message-ID (diff)
From: Marc Zyngier <maz@kernel.org>
To: kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org
Cc: kernel-team@android.com, Will Deacon <will@kernel.org>,
	broonie@kernel.org
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

_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm

WARNING: multiple messages have this Message-ID (diff)
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


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

             reply	other threads:[~2021-10-21 15:11 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-21 15:11 Marc Zyngier [this message]
2021-10-21 15:11 ` [PATCH 0/4] KVM: arm64: Stop mapping current thread_info at EL2 Marc Zyngier
2021-10-21 15:11 ` Marc Zyngier
2021-10-21 15:11 ` [PATCH 1/4] KVM: arm64: Reorder vcpu flag definitions Marc Zyngier
2021-10-21 15:11   ` Marc Zyngier
2021-10-21 15:11   ` Marc Zyngier
2021-10-21 15:11 ` [PATCH 2/4] KVM: arm64: Introduce flag shadowing TIF_FOREIGN_FPSTATE Marc Zyngier
2021-10-21 15:11   ` Marc Zyngier
2021-10-21 15:11   ` Marc Zyngier
2021-10-21 15:24   ` Mark Brown
2021-10-21 15:24     ` Mark Brown
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   ` Marc Zyngier
2021-10-21 15:11   ` 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 15:11   ` Marc Zyngier
2021-10-21 15:11   ` Marc Zyngier
2021-10-21 15:57   ` Mark Brown
2021-10-21 15:57     ` Mark Brown
2021-10-21 15:57     ` Mark Brown
2021-10-27 11:26     ` Marc Zyngier
2021-10-27 11:26       ` Marc Zyngier
2021-10-27 11:26       ` Marc Zyngier

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20211021151124.3098113-1-maz@kernel.org \
    --to=maz@kernel.org \
    --cc=alexandru.elisei@arm.com \
    --cc=broonie@kernel.org \
    --cc=james.morse@arm.com \
    --cc=kernel-team@android.com \
    --cc=kvm@vger.kernel.org \
    --cc=kvmarm@lists.cs.columbia.edu \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=qperret@google.com \
    --cc=suzuki.poulose@arm.com \
    --cc=will@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.