[PATCH 0/3] KVM: arm64: BUG FIX: Correctly handle zero register transfers

From: Pavel Fedin <p.fedin@samsung.com>
To: kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org
Cc: Marc Zyngier <marc.zyngier@arm.com>
Subject: [PATCH 0/3] KVM: arm64: BUG FIX: Correctly handle zero register transfers
Date: Thu, 03 Dec 2015 12:58:39 +0300	[thread overview]
Message-ID: <cover.1449136209.git.p.fedin@samsung.com> (raw)

ARM64 CPU has zero register which is read-only, with a value of 0.
However, KVM currently incorrectly recognizes it being SP (because
Rt == 31, and in struct user_pt_regs 'regs' array is followed by SP),
resulting in invalid value being read, or even SP corruption on write.

The problem has been discovered by performing an operation

 *((volatile int *)reg) = 0;

which compiles as "str xzr, [xx]", and resulted in strange values being
written.

Pavel Fedin (3):
  KVM: arm64: Correctly handle zero register during MMIO
  KVM: arm64: Correctly handle zero register in system register accesses
  KVM: arm64: Get rid of old vcpu_reg()

 arch/arm/include/asm/kvm_emulate.h   | 12 ++++++
 arch/arm/kvm/mmio.c                  |  5 ++-
 arch/arm/kvm/psci.c                  | 20 ++++-----
 arch/arm64/include/asm/kvm_emulate.h | 18 +++++---
 arch/arm64/kvm/handle_exit.c         |  2 +-
 arch/arm64/kvm/sys_regs.c            | 79 ++++++++++++++++++++----------------
 arch/arm64/kvm/sys_regs.h            |  4 +-
 arch/arm64/kvm/sys_regs_generic_v8.c |  2 +-
 8 files changed, 85 insertions(+), 57 deletions(-)

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2.4.4