[PATCH v3 07/32] arm64: KVM: fault injection into a guest

[cdall@cs.columbia.edu (Christoffer Dall)]

On Mon, Apr 08, 2013 at 05:17:09PM +0100, Marc Zyngier wrote:
> Implement the injection of a fault (undefined, data abort or
> prefetch abort) into a 64bit guest.
> 
> Reviewed-by: Christopher Covington <cov@codeaurora.org>
> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
> ---
>  arch/arm64/kvm/inject_fault.c | 118 ++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 118 insertions(+)
>  create mode 100644 arch/arm64/kvm/inject_fault.c
> 
> diff --git a/arch/arm64/kvm/inject_fault.c b/arch/arm64/kvm/inject_fault.c
> new file mode 100644
> index 0000000..2ff3b78
> --- /dev/null
> +++ b/arch/arm64/kvm/inject_fault.c
> @@ -0,0 +1,118 @@
> +/*
> + * Fault injection for 64bit guests.
> + *
> + * Copyright (C) 2012,2013 - ARM Ltd
> + * Author: Marc Zyngier <marc.zyngier@arm.com>
> + *
> + * Based on arch/arm/kvm/emulate.c
> + * Copyright (C) 2012 - Virtual Open Systems and Columbia University
> + * Author: Christoffer Dall <c.dall@virtualopensystems.com>
> + *
> + * This program is free software: you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program.  If not, see <http://www.gnu.org/licenses/>.
> + */
> +
> +#include <linux/kvm_host.h>
> +#include <asm/kvm_emulate.h>
> +#include <asm/esr.h>
> +
> +static void inject_abt64(struct kvm_vcpu *vcpu, bool is_iabt, unsigned long addr)
> +{
> +	unsigned long cpsr = *vcpu_cpsr(vcpu);
> +	int is_aarch32;
> +	u32 esr = 0;
> +
> +	is_aarch32 = vcpu_mode_is_32bit(vcpu);
> +
> +	*vcpu_spsr(vcpu) = cpsr;
> +	*vcpu_elr_el1(vcpu) = *vcpu_pc(vcpu);
> +
> +	*vcpu_cpsr(vcpu) = PSR_MODE_EL1h | PSR_A_BIT | PSR_F_BIT | PSR_I_BIT;
> +	*vcpu_pc(vcpu) = vcpu_sys_reg(vcpu, VBAR_EL1) + 0x200;

consider a define for the 0x200?

> +
> +	vcpu_sys_reg(vcpu, FAR_EL1) = addr;
> +
> +	/*
> +	 * Build an {i,d}abort, depending on the level and the
> +	 * instruction set. Report an external synchronous abort.
> +	 */
> +	if (kvm_vcpu_trap_il_is32bit(vcpu))
> +		esr |= ESR_EL1_IL;
> +
> +	if (is_aarch32 || (cpsr & PSR_MODE_MASK) == PSR_MODE_EL0t)
> +		esr |= (ESR_EL1_EC_IABT_EL0 << ESR_EL1_EC_SHIFT);
> +	else
> +		esr |= (ESR_EL1_EC_IABT_EL1 << ESR_EL1_EC_SHIFT);

why is it assumed that the abort must come from EL0 if the vcpu is in
aarch32 mode?

> +
> +	if (!is_iabt)
> +		esr |= ESR_EL1_EC_DABT_EL0;

this is slightly confusing unless you actually look at the definitions
and realize that or'ing on that extra bit works both in i- and d-abt
cases.

> +
> +	vcpu_sys_reg(vcpu, ESR_EL1) = esr | 0x10; /* External abort */
> +}
> +
> +static void inject_undef64(struct kvm_vcpu *vcpu)
> +{
> +	unsigned long cpsr = *vcpu_cpsr(vcpu);
> +	u32 esr = (ESR_EL1_EC_UNKNOWN << ESR_EL1_EC_SHIFT);
> +
> +	*vcpu_spsr(vcpu) = cpsr;
> +	*vcpu_elr_el1(vcpu) = *vcpu_pc(vcpu);
> +
> +	*vcpu_cpsr(vcpu) = PSR_MODE_EL1h | PSR_F_BIT | PSR_I_BIT;

would it make sense to have a define for a common set of these bits or
is this explicitly defined per exception type in the specs?

> +	*vcpu_pc(vcpu) = vcpu_sys_reg(vcpu, VBAR_EL1) + 0x200;
> +
> +	/*
> +	 * Build an unknown exception, depending on the instruction
> +	 * set.
> +	 */
> +	if (kvm_vcpu_trap_il_is32bit(vcpu))
> +		esr |= ESR_EL1_IL;
> +
> +	vcpu_sys_reg(vcpu, ESR_EL1) = esr;
> +}
> +
> +/**
> + * kvm_inject_dabt - inject a data abort into the guest
> + * @vcpu: The VCPU to receive the undefined exception
> + * @addr: The address to report in the DFAR
> + *
> + * It is assumed that this code is called from the VCPU thread and that the
> + * VCPU therefore is not currently executing guest code.
> + */
> +void kvm_inject_dabt(struct kvm_vcpu *vcpu, unsigned long addr)
> +{
> +	inject_abt64(vcpu, false, addr);
> +}
> +
> +/**
> + * kvm_inject_pabt - inject a prefetch abort into the guest
> + * @vcpu: The VCPU to receive the undefined exception
> + * @addr: The address to report in the DFAR
> + *
> + * It is assumed that this code is called from the VCPU thread and that the
> + * VCPU therefore is not currently executing guest code.
> + */
> +void kvm_inject_pabt(struct kvm_vcpu *vcpu, unsigned long addr)
> +{
> +	inject_abt64(vcpu, true, addr);
> +}
> +
> +/**
> + * kvm_inject_undefined - inject an undefined instruction into the guest
> + *
> + * It is assumed that this code is called from the VCPU thread and that the
> + * VCPU therefore is not currently executing guest code.
> + */
> +void kvm_inject_undefined(struct kvm_vcpu *vcpu)
> +{
> +	inject_undef64(vcpu);
> +}
> -- 
> 1.8.1.4
> 
> 
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