Commit 0d640732 authored Nov 09, 2018 by Mark Rutland Committed by Marc Zyngier Dec 18, 2018

arm64: KVM: Skip MMIO insn after emulation



When we emulate an MMIO instruction, we advance the CPU state within
decode_hsr(), before emulating the instruction effects.

Having this logic in decode_hsr() is opaque, and advancing the state
before emulation is problematic. It gets in the way of applying
consistent single-step logic, and it prevents us from being able to fail
an MMIO instruction with a synchronous exception.

Clean this up by only advancing the CPU state *after* the effects of the
instruction are emulated.

Cc: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Christoffer Dall <christoffer.dall@arm.com>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

parent 2e6e902d

virt/kvm/arm/mmio.c

+6 −5

Original line number	Diff line number	Diff line
		@@ -117,6 +117,12 @@ int kvm_handle_mmio_return(struct kvm_vcpu vcpu, struct kvm_run run)
		vcpu_set_reg(vcpu, vcpu->arch.mmio_decode.rt, data);
		}

		/*
		* The MMIO instruction is emulated and should not be re-executed
		* in the guest.
		*/
		kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));

		return 0;
		}

		@@ -144,11 +150,6 @@ static int decode_hsr(struct kvm_vcpu vcpu, bool is_write, int *len)
		vcpu->arch.mmio_decode.sign_extend = sign_extend;
		vcpu->arch.mmio_decode.rt = rt;

		/*
		* The MMIO instruction is emulated and should not be re-executed
		* in the guest.
		*/
		kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));
		return 0;
		}

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