[PATCH v6 44/64] KVM: arm64: nv: Add handling of EL2-specific timer registers

[Alexandru Elisei]

Hi,

On Fri, Jan 28, 2022 at 12:18:52PM +0000, Marc Zyngier wrote:
> Add the required handling for EL2 and EL02 registers, as
> well as EL1 registers used in the E2H context.
> 
> Signed-off-by: Marc Zyngier <maz at kernel.org>
> ---
>  arch/arm64/include/asm/sysreg.h |  6 +++
>  arch/arm64/kvm/sys_regs.c       | 87 +++++++++++++++++++++++++++++++++
>  2 files changed, 93 insertions(+)
> 
> diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
> index 41c3603a3f29..ff6d3af8ed34 100644
> --- a/arch/arm64/include/asm/sysreg.h
> +++ b/arch/arm64/include/asm/sysreg.h
> @@ -626,6 +626,12 @@
>  
>  #define SYS_CNTVOFF_EL2			sys_reg(3, 4, 14, 0, 3)
>  #define SYS_CNTHCTL_EL2			sys_reg(3, 4, 14, 1, 0)
> +#define SYS_CNTHP_TVAL_EL2		sys_reg(3, 4, 14, 2, 0)
> +#define SYS_CNTHP_CTL_EL2		sys_reg(3, 4, 14, 2, 1)
> +#define SYS_CNTHP_CVAL_EL2		sys_reg(3, 4, 14, 2, 2)
> +#define SYS_CNTHV_TVAL_EL2		sys_reg(3, 4, 14, 3, 0)
> +#define SYS_CNTHV_CTL_EL2		sys_reg(3, 4, 14, 3, 1)
> +#define SYS_CNTHV_CVAL_EL2		sys_reg(3, 4, 14, 3, 2)
>  
>  /* VHE encodings for architectural EL0/1 system registers */
>  #define SYS_SCTLR_EL12			sys_reg(3, 5, 1, 0, 0)
> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> index bbc58930a5eb..f2452e76156c 100644
> --- a/arch/arm64/kvm/sys_regs.c
> +++ b/arch/arm64/kvm/sys_regs.c
> @@ -1274,20 +1274,92 @@ static bool access_arch_timer(struct kvm_vcpu *vcpu,
>  
>  	switch (reg) {
>  	case SYS_CNTP_TVAL_EL0:
> +		if (vcpu_is_el2(vcpu) && vcpu_el2_e2h_is_set(vcpu))

According to ARM DDI 0487G.a, page D13-4157, if PSTATE is EL0 then accesses are
also redirected to CNTHP_TVAL_EL2 (under certain conditions).

> +			tmr = TIMER_HPTIMER;
> +		else
> +			tmr = TIMER_PTIMER;

What happens when the guest hypervisor has enabled traps for this register?
Shouldn't those also be forwarded?

> +		treg = TIMER_REG_TVAL;
> +		break;
> +
>  	case SYS_AARCH32_CNTP_TVAL:
> +	case SYS_CNTP_TVAL_EL02:

Shouldn't KVM inject an undefined exception if PSTATE is EL2 and virtual
HCR_EL2.E2H = 0? Shouldn't KVM forward the trap if PSTATE is EL1 and virtual
HCR_EL2.NV = 1? The same applies to all EL02 encodings.

>  		tmr = TIMER_PTIMER;
>  		treg = TIMER_REG_TVAL;
>  		break;
> +
> +	case SYS_CNTV_TVAL_EL02:
> +		tmr = TIMER_VTIMER;
> +		treg = TIMER_REG_TVAL;
> +		break;
> +
> +	case SYS_CNTHP_TVAL_EL2:
> +		tmr = TIMER_HPTIMER;
> +		treg = TIMER_REG_TVAL;
> +		break;
> +
> +	case SYS_CNTHV_TVAL_EL2:
> +		tmr = TIMER_HVTIMER;
> +		treg = TIMER_REG_TVAL;

Shouldn't KVM inject an undefined exception if guest PSTATE is EL1 and virtual
HCR_EL2.NV = 0? Shouldn't KVM forward the trap if PSTATE is EL1 and
HCR_EL2.NV = 1? Same for the other _EL2 registers.

Thanks,
Alex

> +		break;
> +
>  	case SYS_CNTP_CTL_EL0:
> +		if (vcpu_is_el2(vcpu) && vcpu_el2_e2h_is_set(vcpu))
> +			tmr = TIMER_HPTIMER;
> +		else
> +			tmr = TIMER_PTIMER;
> +		treg = TIMER_REG_CTL;
> +		break;
> +
>  	case SYS_AARCH32_CNTP_CTL:
> +	case SYS_CNTP_CTL_EL02:
>  		tmr = TIMER_PTIMER;
>  		treg = TIMER_REG_CTL;
>  		break;
> +
> +	case SYS_CNTV_CTL_EL02:
> +		tmr = TIMER_VTIMER;
> +		treg = TIMER_REG_CTL;
> +		break;
> +
> +	case SYS_CNTHP_CTL_EL2:
> +		tmr = TIMER_HPTIMER;
> +		treg = TIMER_REG_CTL;
> +		break;
> +
> +	case SYS_CNTHV_CTL_EL2:
> +		tmr = TIMER_HVTIMER;
> +		treg = TIMER_REG_CTL;
> +		break;
> +
>  	case SYS_CNTP_CVAL_EL0:
> +		if (vcpu_is_el2(vcpu) && vcpu_el2_e2h_is_set(vcpu))
> +			tmr = TIMER_HPTIMER;
> +		else
> +			tmr = TIMER_PTIMER;
> +		treg = TIMER_REG_CVAL;
> +		break;
> +
>  	case SYS_AARCH32_CNTP_CVAL:
> +	case SYS_CNTP_CVAL_EL02:
>  		tmr = TIMER_PTIMER;
>  		treg = TIMER_REG_CVAL;
>  		break;
> +
> +	case SYS_CNTV_CVAL_EL02:
> +		tmr = TIMER_VTIMER;
> +		treg = TIMER_REG_CVAL;
> +		break;
> +
> +	case SYS_CNTHP_CVAL_EL2:
> +		tmr = TIMER_HPTIMER;
> +		treg = TIMER_REG_CVAL;
> +		break;
> +
> +	case SYS_CNTHV_CVAL_EL2:
> +		tmr = TIMER_HVTIMER;
> +		treg = TIMER_REG_CVAL;
> +		break;
> +
>  	case SYS_CNTVOFF_EL2:
>  		tmr = TIMER_VTIMER;
>  		treg = TIMER_REG_VOFF;
> @@ -2220,6 +2292,13 @@ static const struct sys_reg_desc sys_reg_descs[] = {
>  	{ SYS_DESC(SYS_CNTVOFF_EL2), access_arch_timer },
>  	EL2_REG(CNTHCTL_EL2, access_rw, reset_val, 0),
>  
> +	{ SYS_DESC(SYS_CNTHP_TVAL_EL2), access_arch_timer },
> +	{ SYS_DESC(SYS_CNTHP_CTL_EL2), access_arch_timer },
> +	{ SYS_DESC(SYS_CNTHP_CVAL_EL2), access_arch_timer },
> +	{ SYS_DESC(SYS_CNTHV_TVAL_EL2), access_arch_timer },
> +	{ SYS_DESC(SYS_CNTHV_CTL_EL2), access_arch_timer },
> +	{ SYS_DESC(SYS_CNTHV_CVAL_EL2), access_arch_timer },
> +
>  	EL12_REG(SCTLR, access_vm_reg, reset_val, 0x00C50078),
>  	EL12_REG(CPACR, access_rw, reset_val, 0),
>  	EL12_REG(TTBR0, access_vm_reg, reset_unknown, 0),
> @@ -2237,6 +2316,14 @@ static const struct sys_reg_desc sys_reg_descs[] = {
>  	EL12_REG(CONTEXTIDR, access_vm_reg, reset_val, 0),
>  	EL12_REG(CNTKCTL, access_rw, reset_val, 0),
>  
> +	{ SYS_DESC(SYS_CNTP_TVAL_EL02), access_arch_timer },
> +	{ SYS_DESC(SYS_CNTP_CTL_EL02), access_arch_timer },
> +	{ SYS_DESC(SYS_CNTP_CVAL_EL02), access_arch_timer },
> +
> +	{ SYS_DESC(SYS_CNTV_TVAL_EL02), access_arch_timer },
> +	{ SYS_DESC(SYS_CNTV_CTL_EL02), access_arch_timer },
> +	{ SYS_DESC(SYS_CNTV_CVAL_EL02), access_arch_timer },
> +
>  	EL2_REG(SP_EL2, NULL, reset_unknown, 0),
>  };
>  
> -- 
> 2.30.2
>