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(-) -- 2.4.4 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
