Subject: [PATCH v2 10/10] ARM: KVM: add world-switch for AMAIR{0,1}

From: [email-masked] (Christoffer Dall)
Date: Wed, 29 Jan 2014 12:08:28 -0800

On Wed, Jan 22, 2014 at 02:56:42PM +0000, Marc Zyngier wrote:
> HCR.TVM traps (among other things) accesses to AMAIR0 and AMAIR1.
> In order to minimise the amount of surprise a guest could generate by
> trying to access these registers with caches off, add them to the
> list of registers we switch/handle.
> 
> Signed-off-by: Marc Zyngier <[email-masked]>
> ---
>  arch/arm/include/asm/kvm_asm.h |  4 +++-
>  arch/arm/kvm/coproc.c          |  6 ++++++
>  arch/arm/kvm/interrupts_head.S | 12 ++++++++++--
>  3 files changed, 19 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/arm/include/asm/kvm_asm.h b/arch/arm/include/asm/kvm_asm.h
> index 661da11..53b3c4a 100644
> --- a/arch/arm/include/asm/kvm_asm.h
> +++ b/arch/arm/include/asm/kvm_asm.h
> @@ -48,7 +48,9 @@
>  #define c13_TID_URO	26	/* Thread ID, User R/O */
>  #define c13_TID_PRIV	27	/* Thread ID, Privileged */
>  #define c14_CNTKCTL	28	/* Timer Control Register (PL1) */
> -#define NR_CP15_REGS	29	/* Number of regs (incl. invalid) */
> +#define c10_AMAIR0	29	/* Auxilary Memory Attribute Indirection Reg0 */
> +#define c10_AMAIR1	30	/* Auxilary Memory Attribute Indirection Reg1 */
> +#define NR_CP15_REGS	31	/* Number of regs (incl. invalid) */
>  
>  #define ARM_EXCEPTION_RESET	  0
>  #define ARM_EXCEPTION_UNDEFINED   1
> diff --git a/arch/arm/kvm/coproc.c b/arch/arm/kvm/coproc.c
> index 1839770..539f6d4 100644
> --- a/arch/arm/kvm/coproc.c
> +++ b/arch/arm/kvm/coproc.c
> @@ -381,6 +381,12 @@ static const struct coproc_reg cp15_regs[] = {
>  	{ CRn(10), CRm( 2), Op1( 0), Op2( 1), is32,
>  			access_vm_reg, reset_unknown, c10_NMRR},
>  
> +	/* AMAIR0/AMAIR1: swapped by interrupt.S. */
> +	{ CRn(10), CRm( 3), Op1( 0), Op2( 0), is32,
> +			access_vm_reg, reset_unknown, c10_AMAIR0},
> +	{ CRn(10), CRm( 3), Op1( 0), Op2( 1), is32,
> +			access_vm_reg, reset_unknown, c10_AMAIR1},
> +
>  	/* VBAR: swapped by interrupt.S. */
>  	{ CRn(12), CRm( 0), Op1( 0), Op2( 0), is32,
>  			NULL, reset_val, c12_VBAR, 0x00000000 },
> diff --git a/arch/arm/kvm/interrupts_head.S b/arch/arm/kvm/interrupts_head.S
> index 7cb41e1..e4eaf30 100644
> --- a/arch/arm/kvm/interrupts_head.S
> +++ b/arch/arm/kvm/interrupts_head.S
> @@ -303,13 +303,17 @@ vcpu	.req	r0		@ vcpu pointer always in r0
>  
>  	mrc	p15, 0, r2, c14, c1, 0	@ CNTKCTL
>  	mrrc	p15, 0, r4, r5, c7	@ PAR
> +	mrc	p15, 0, r6, c10, c3, 0	@ AMAIR0
> +	mrc	p15, 0, r7, c10, c3, 1	@ AMAIR1
>  
>  	.if \store_to_vcpu == 0
> -	push	{r2,r4-r5}
> +	push	{r2,r4-r7}
>  	.else
>  	str	r2, [vcpu, #CP15_OFFSET(c14_CNTKCTL)]
>  	add	r12, vcpu, #CP15_OFFSET(c7_PAR)
>  	strd	r4, r5, [r12]
> +	str	r6, [vcpu, #CP15_OFFSET(c10_AMAIR0)]
> +	str	r7, [vcpu, #CP15_OFFSET(c10_AMAIR1)]
>  	.endif
>  .endm
>  
> @@ -322,15 +326,19 @@ vcpu	.req	r0		@ vcpu pointer always in r0
>   */
>  .macro write_cp15_state read_from_vcpu
>  	.if \read_from_vcpu == 0
> -	pop	{r2,r4-r5}
> +	pop	{r2,r4-r7}
>  	.else
>  	ldr	r2, [vcpu, #CP15_OFFSET(c14_CNTKCTL)]
>  	add	r12, vcpu, #CP15_OFFSET(c7_PAR)
>  	ldrd	r4, r5, [r12]
> +	ldr	r6, [vcpu, #CP15_OFFSET(c10_AMAIR0)]
> +	ldr	r7, [vcpu, #CP15_OFFSET(c10_AMAIR1)]
>  	.endif
>  
>  	mcr	p15, 0, r2, c14, c1, 0	@ CNTKCTL
>  	mcrr	p15, 0, r4, r5, c7	@ PAR
> +	mcr	p15, 0, r6, c10, c3, 0	@ AMAIR0
> +	mcr	p15, 0, r7, c10, c3, 1	@ AMAIR1
>  
>  	.if \read_from_vcpu == 0
>  	pop	{r2-r12}
> -- 
> 1.8.3.4
> 

Looks good, but shouldn't this be added before patch 9 to maintain
functional bisectability?

Otherwise:
Reviewed-by: Christoffer Dall <[email-masked]>