[PATCH 0/3] KVM: arm64: Fix get-reg-list regression

From: Andrew Jones <drjones@redhat.com>
To: kvmarm@lists.cs.columbia.edu
Cc: maz@kernel.org, xu910121@sina.com, Dave.Martin@arm.com
Subject: [PATCH 0/3] KVM: arm64: Fix get-reg-list regression
Date: Thu, 29 Oct 2020 21:11:02 +0100	[thread overview]
Message-ID: <20201029201105.101910-1-drjones@redhat.com> (raw)

张东旭 <xu910121@sina.com> reported a regression seen with CentOS
when migrating from an old kernel to a new one. The problem was
that QEMU rejected the migration since KVM_GET_REG_LIST reported
a register was missing on the destination. Extra registers are OK
on the destination, but not missing ones. The regression reproduces
with upstream kernels when migrating from a 4.15 or later kernel,
up to one with commit 73433762fcae ("KVM: arm64/sve: System register
context switch and access support"), to a kernel that includes that
commit, e.g. the latest mainline (5.10-rc1).

The first patch of this series is the fix. The next two patches,
which don't have any intended functional changes, allow ID_SANITISED
to be used for registers that flip between exposing features and
being RAZ, which allows some code to be removed.

Andrew Jones (3):
  KVM: arm64: Don't hide ID registers from userspace
  KVM: arm64: Check RAZ visibility in ID register accessors
  KVM: arm64: Remove AA64ZFR0_EL1 accessors

 arch/arm64/kvm/sys_regs.c | 96 +++++++++++----------------------------
 arch/arm64/kvm/sys_regs.h | 20 ++++++++
 2 files changed, 47 insertions(+), 69 deletions(-)

-- 
2.27.0

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