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

[marc.zyngier@arm.com (Marc Zyngier)]

On 23/04/13 23:57, Christoffer Dall wrote:
> 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?

Yeah, I think Will already mentioned this.

>> +
>> +	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?

We're injecting a fault into a VM that runs with a 64bit EL1. So if we
end-up faulting in 32bit code, it must come from EL0.

>> +
>> +	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.

Blame Christopher for that, he came up with the idea... ;-)

>> +
>> +	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?

Maybe. Not sure that would be any clearer though...

	M.
-- 
Jazz is not dead. It just smells funny...