linux-kernel - Re: [RFC 09/55] KVM: arm64: Set shadow EL1 registers for virtual EL2 execution

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Message-ID: <20170222111952.GE26976@cbox>
Date:   Wed, 22 Feb 2017 12:19:52 +0100
From:   Christoffer Dall <cdall@...aro.org>
To:     Jintack Lim <jintack@...columbia.edu>
Cc:     christoffer.dall@...aro.org, marc.zyngier@....com,
        pbonzini@...hat.com, rkrcmar@...hat.com, linux@...linux.org.uk,
        catalin.marinas@....com, will.deacon@....com,
        vladimir.murzin@....com, suzuki.poulose@....com,
        mark.rutland@....com, james.morse@....com,
        lorenzo.pieralisi@....com, kevin.brodsky@....com,
        wcohen@...hat.com, shankerd@...eaurora.org, geoff@...radead.org,
        andre.przywara@....com, eric.auger@...hat.com,
        anna-maria@...utronix.de, shihwei@...columbia.edu,
        linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC 09/55] KVM: arm64: Set shadow EL1 registers for virtual EL2
 execution

On Mon, Jan 09, 2017 at 01:24:05AM -0500, Jintack Lim wrote:
> From: Christoffer Dall <christoffer.dall@...aro.org>
> 
> When entering virtual EL2, we need to reflect virtual EL2 register
> states to corresponding shadow EL1 registers. We can simply copy them if
> their formats are identical.  Otherwise, we need to convert EL2 register
> state to EL1 register state.
> 
> Signed-off-by: Christoffer Dall <christoffer.dall@...aro.org>
> Signed-off-by: Jintack Lim <jintack@...columbia.edu>
> ---
>  arch/arm64/kvm/context.c | 71 ++++++++++++++++++++++++++++++++++++++++++++++++

Looking at this again, I'm not sure 'context.c' is a very meaningful
name.

>  1 file changed, 71 insertions(+)
> 
> diff --git a/arch/arm64/kvm/context.c b/arch/arm64/kvm/context.c
> index acb4b1e..2e9e386 100644
> --- a/arch/arm64/kvm/context.c
> +++ b/arch/arm64/kvm/context.c
> @@ -17,6 +17,76 @@
>  
>  #include <linux/kvm_host.h>
>  #include <asm/kvm_emulate.h>
> +#include <asm/esr.h>
> +
> +struct el1_el2_map {
> +	enum vcpu_sysreg	el1;
> +	enum el2_regs		el2;
> +};
> +
> +/*
> + * List of EL2 registers which can be directly applied to EL1 registers to
> + * emulate running EL2 in EL1.  The EL1 registers here must either be trapped
> + * or paravirtualized in EL1.

This series doesn't deal with paravirtualizaion but only targets 8.3 so
we should clean up references to paravirtualization.

> + */
> +static const struct el1_el2_map el1_el2_map[] = {
> +	{ AMAIR_EL1, AMAIR_EL2 },
> +	{ MAIR_EL1, MAIR_EL2 },
> +	{ TTBR0_EL1, TTBR0_EL2 },
> +	{ ACTLR_EL1, ACTLR_EL2 },
> +	{ AFSR0_EL1, AFSR0_EL2 },
> +	{ AFSR1_EL1, AFSR1_EL2 },
> +	{ SCTLR_EL1, SCTLR_EL2 },
> +	{ VBAR_EL1, VBAR_EL2 },
> +};
> +
> +static inline u64 tcr_el2_ips_to_tcr_el1_ps(u64 tcr_el2)
> +{
> +	return ((tcr_el2 & TCR_EL2_PS_MASK) >> TCR_EL2_PS_SHIFT)
> +		<< TCR_IPS_SHIFT;
> +}
> +
> +static inline u64 cptr_el2_to_cpacr_el1(u64 cptr_el2)
> +{
> +	u64 cpacr_el1 = 0;
> +
> +	if (!(cptr_el2 & CPTR_EL2_TFP))
> +		cpacr_el1 |= CPACR_EL1_FPEN;
> +	if (cptr_el2 & CPTR_EL2_TTA)
> +		cpacr_el1 |= CPACR_EL1_TTA;
> +
> +	return cpacr_el1;
> +}
> +
> +static void create_shadow_el1_sysregs(struct kvm_vcpu *vcpu)
> +{
> +	u64 *s_sys_regs = vcpu->arch.ctxt.shadow_sys_regs;
> +	u64 *el2_regs = vcpu->arch.ctxt.el2_regs;
> +	u64 tcr_el2;
> +	int i;
> +
> +	for (i = 0; i < ARRAY_SIZE(el1_el2_map); i++) {
> +		const struct el1_el2_map *map = &el1_el2_map[i];
> +
> +		s_sys_regs[map->el1] = el2_regs[map->el2];
> +	}
> +
> +	tcr_el2 = el2_regs[TCR_EL2];
> +	s_sys_regs[TCR_EL1] =
> +		TCR_EPD1 |	/* disable TTBR1_EL1 */
> +		((tcr_el2 & TCR_EL2_TBI) ? TCR_TBI0 : 0) |
> +		tcr_el2_ips_to_tcr_el1_ps(tcr_el2) |
> +		(tcr_el2 & TCR_EL2_TG0_MASK) |
> +		(tcr_el2 & TCR_EL2_ORGN0_MASK) |
> +		(tcr_el2 & TCR_EL2_IRGN0_MASK) |
> +		(tcr_el2 & TCR_EL2_T0SZ_MASK);
> +
> +	/* Rely on separate VMID for VA context, always use ASID 0 */
> +	s_sys_regs[TTBR0_EL1] &= ~GENMASK_ULL(63, 48);
> +	s_sys_regs[TTBR1_EL1] = 0;
> +
> +	s_sys_regs[CPACR_EL1] = cptr_el2_to_cpacr_el1(el2_regs[CPTR_EL2]);
> +}
>  
>  /**
>   * kvm_arm_setup_shadow_state -- prepare shadow state based on emulated mode
> @@ -37,6 +107,7 @@ void kvm_arm_setup_shadow_state(struct kvm_vcpu *vcpu)
>  		else
>  			ctxt->hw_pstate |= PSR_MODE_EL1t;
>  
> +		create_shadow_el1_sysregs(vcpu);
>  		ctxt->hw_sys_regs = ctxt->shadow_sys_regs;
>  		ctxt->hw_sp_el1 = ctxt->el2_regs[SP_EL2];
>  	} else {
> -- 
> 1.9.1
> 
>