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SubjectRe: [RFC 06/55] KVM: arm64: Add EL2 execution context for nesting
On Mon, Jan 09, 2017 at 01:24:02AM -0500, Jintack Lim wrote:
> With the nested virtualization support, the context of the guest
> includes EL2 register states. The host manages a set of virtual EL2
> registers. In addition to that, the guest hypervisor supposed to run in
> EL2 is now deprivilaged and runs in EL1. So, the host also manages a set
> of shadow system registers to be able to run the guest hypervisor in
> EL1.
>
> Signed-off-by: Jintack Lim <jintack@cs.columbia.edu>
> Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
> ---
> arch/arm64/include/asm/kvm_host.h | 54 +++++++++++++++++++++++++++++++++++++++
> 1 file changed, 54 insertions(+)
>
> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> index c0c8b02..ed78d73 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -146,6 +146,42 @@ enum vcpu_sysreg {
> NR_SYS_REGS /* Nothing after this line! */
> };
>
> +enum el2_regs {
> + ELR_EL2,
> + SPSR_EL2,
> + SP_EL2,
> + AMAIR_EL2,
> + MAIR_EL2,
> + TCR_EL2,
> + TTBR0_EL2,
> + VTCR_EL2,
> + VTTBR_EL2,
> + VMPIDR_EL2,
> + VPIDR_EL2, /* 10 */
> + MDCR_EL2,
> + CNTHCTL_EL2,
> + CNTHP_CTL_EL2,
> + CNTHP_CVAL_EL2,
> + CNTHP_TVAL_EL2,
> + CNTVOFF_EL2,
> + ACTLR_EL2,
> + AFSR0_EL2,
> + AFSR1_EL2,
> + CPTR_EL2, /* 20 */
> + ESR_EL2,
> + FAR_EL2,
> + HACR_EL2,
> + HCR_EL2,
> + HPFAR_EL2,
> + HSTR_EL2,
> + RMR_EL2,
> + RVBAR_EL2,
> + SCTLR_EL2,
> + TPIDR_EL2, /* 30 */
> + VBAR_EL2,
> + NR_EL2_REGS /* Nothing after this line! */
> +};

Why do we have a separate enum and array for the EL2 regs and not simply
expand vcpu_sysreg ?

> +
> /* 32bit mapping */
> #define c0_MPIDR (MPIDR_EL1 * 2) /* MultiProcessor ID Register */
> #define c0_CSSELR (CSSELR_EL1 * 2)/* Cache Size Selection Register */
> @@ -193,6 +229,23 @@ struct kvm_cpu_context {
> u64 sys_regs[NR_SYS_REGS];
> u32 copro[NR_COPRO_REGS];
> };
> +
> + u64 el2_regs[NR_EL2_REGS]; /* only used for nesting */
> + u64 shadow_sys_regs[NR_SYS_REGS]; /* only used for virtual EL2 */
> +
> + /*
> + * hw_* will be used when switching to a VM. They point to either
> + * the virtual EL2 or EL1/EL0 context depending on vcpu mode.

don't they either point to the shadow sys regs or the the normal EL1
sysregs?

> + */
> +
> + /* pointing shadow_sys_regs or sys_regs */

that's what this comment seems to indicate, so there's some duplicity
here.

> + u64 *hw_sys_regs;
> +
> + /* copy of either gp_regs.sp_el1 or el2_regs[SP_EL2] */
> + u64 hw_sp_el1;
> +
> + /* pstate written to SPSR_EL2 */
> + u64 hw_pstate;
> };
>
> typedef struct kvm_cpu_context kvm_cpu_context_t;
> @@ -277,6 +330,7 @@ struct kvm_vcpu_arch {
>
> #define vcpu_gp_regs(v) (&(v)->arch.ctxt.gp_regs)
> #define vcpu_sys_reg(v,r) ((v)->arch.ctxt.sys_regs[(r)])
> +#define vcpu_el2_reg(v, r) ((v)->arch.ctxt.el2_regs[(r)])
> /*
> * CP14 and CP15 live in the same array, as they are backed by the
> * same system registers.
> --
> 1.9.1
>
>

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