[PATCH 0/3] KVM: arm64: Fix handling of S1PTW S2 fault on RO memslots

From: Marc Zyngier <maz@kernel.org>
To: <kvmarm@lists.cs.columbia.edu>, <kvmarm@lists.linux.dev>,
	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>,
	Oliver Upton <oliver.upton@linux.dev>,
	Ard Biesheuvel <ardb@kernel.org>, Will Deacon <will@kernel.org>,
	Quentin Perret <qperret@google.com>
Subject: [PATCH 0/3] KVM: arm64: Fix handling of S1PTW S2 fault on RO memslots
Date: Tue, 20 Dec 2022 20:09:20 +0000	[thread overview]
Message-ID: <20221220200923.1532710-1-maz@kernel.org> (raw)

Recent developments on the EFI front have resulted in guests that
simply won't boot if the page tables are in a read-only memslot and
that you're a bit unlucky in the way S2 gets paged in... The core
issue is related to the fact that we treat a S1PTW as a write, which
is close enough to what needs to be done. Until to get to RO memslots.

The first patch fixes this and is definitely a stable candidate. It
splits the faulting of page tables in two steps (RO translation fault,
followed by a writable permission fault -- should it even happen).
The second one is a potential optimisation. I'm not even sure it is
worth it. The last patch is totally optional, only tangentially
related, and randomly repainting stuff (maybe that's contagious, who
knows).

The whole thing is on top of Linus' tree as of today. The reason for
this very random choice is that there is a patch in v6.1-rc7 that
hides the problem, and that patch is reverted in rc8 (see commit
0ba09b1733878afe838fe35c310715fda3d46428). I also wanted to avoid
conflicts with kvmarm/next, so here you go.

I've tested the series on A55, M1 and M2. The original issue seems to
trigger best with 16kB pages, so please test with *other* page sizes!

	M.

Marc Zyngier (3):
  KVM: arm64: Fix S1PTW handling on RO memslots
  KVM: arm64: Handle S1PTW translation with TCR_HA set as a write
  KVM: arm64: Convert FSC_* over to ESR_ELx_FSC_*

 arch/arm64/include/asm/esr.h            |  9 ++++
 arch/arm64/include/asm/kvm_arm.h        | 15 -------
 arch/arm64/include/asm/kvm_emulate.h    | 60 ++++++++++++++++++++-----
 arch/arm64/kvm/hyp/include/hyp/fault.h  |  2 +-
 arch/arm64/kvm/hyp/include/hyp/switch.h |  2 +-
 arch/arm64/kvm/mmu.c                    | 21 +++++----
 6 files changed, 71 insertions(+), 38 deletions(-)

-- 
2.34.1

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