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SubjectRe: [RFC 12/55] KVM: arm64: Handle EL2 register access traps
On Mon, Jan 09, 2017 at 01:24:08AM -0500, Jintack Lim wrote:
> ARM v8.3 introduces a new bit in the HCR_EL2, which is the NV bit. When
> this bit is set, accessing EL2 registers in EL1 traps to EL2. In
> addition, executing following instructions in EL1 will trap to EL2 -

the following:

So these instructions trap:
- tlbi
- at
- eret
- mrs/msr accessgin sp_el1

And they would previously undef at EL1, but now trap to EL2?

> tlbi and at instructions which are undefined when exectued in EL1, eret
> instruction, msr/mrs instructions to access SP_EL1.

this is a bit confusing to read.

>
> This patch handles traps due to accessing EL2 registers in EL1. The
> host hypervisor keeps EL2 register values in memory, and will use them
> to emulate the behavior that the guest hypervisor expects from the
> hardware.
>
> Subsequent patches will handle other kinds of traps.
>
> Signed-off-by: Jintack Lim <jintack@cs.columbia.edu>
> ---
> arch/arm64/kvm/sys_regs.c | 119 ++++++++++++++++++++++++++++++++++++++++++++++
> arch/arm64/kvm/sys_regs.h | 7 +++
> 2 files changed, 126 insertions(+)
>
> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> index 7cef94f..4158f2f 100644
> --- a/arch/arm64/kvm/sys_regs.c
> +++ b/arch/arm64/kvm/sys_regs.c
> @@ -873,6 +873,18 @@ static bool access_cntp_cval(struct kvm_vcpu *vcpu,
> return true;
> }
>
> +static bool trap_el2_reg(struct kvm_vcpu *vcpu,
> + struct sys_reg_params *p,
> + const struct sys_reg_desc *r)
> +{
> + if (!p->is_write)
> + p->regval = vcpu_el2_reg(vcpu, r->reg);
> + else
> + vcpu_el2_reg(vcpu, r->reg) = p->regval;
> +
> + return true;
> +}
> +
> /*
> * Architected system registers.
> * Important: Must be sorted ascending by Op0, Op1, CRn, CRm, Op2
> @@ -1163,15 +1175,122 @@ static bool access_cntp_cval(struct kvm_vcpu *vcpu,
> { Op0(0b11), Op1(0b011), CRn(0b1110), CRm(0b1111), Op2(0b111),
> access_pmu_evtyper, reset_val, PMCCFILTR_EL0, 0 },
>
> + /* VPIDR_EL2 */
> + { Op0(0b11), Op1(0b100), CRn(0b0000), CRm(0b0000), Op2(0b000),
> + trap_el2_reg, reset_el2_val, VPIDR_EL2, 0 },
> + /* VMPIDR_EL2 */
> + { Op0(0b11), Op1(0b100), CRn(0b0000), CRm(0b0000), Op2(0b101),
> + trap_el2_reg, reset_el2_val, VMPIDR_EL2, 0 },
> +
> + /* SCTLR_EL2 */
> + { Op0(0b11), Op1(0b100), CRn(0b0001), CRm(0b0000), Op2(0b000),
> + trap_el2_reg, reset_el2_val, SCTLR_EL2, 0 },
> + /* ACTLR_EL2 */
> + { Op0(0b11), Op1(0b100), CRn(0b0001), CRm(0b0000), Op2(0b001),
> + trap_el2_reg, reset_el2_val, ACTLR_EL2, 0 },
> + /* HCR_EL2 */
> + { Op0(0b11), Op1(0b100), CRn(0b0001), CRm(0b0001), Op2(0b000),
> + trap_el2_reg, reset_el2_val, HCR_EL2, 0 },
> + /* MDCR_EL2 */
> + { Op0(0b11), Op1(0b100), CRn(0b0001), CRm(0b0001), Op2(0b001),
> + trap_el2_reg, reset_el2_val, MDCR_EL2, 0 },
> + /* CPTR_EL2 */
> + { Op0(0b11), Op1(0b100), CRn(0b0001), CRm(0b0001), Op2(0b010),
> + trap_el2_reg, reset_el2_val, CPTR_EL2, 0 },
> + /* HSTR_EL2 */
> + { Op0(0b11), Op1(0b100), CRn(0b0001), CRm(0b0001), Op2(0b011),
> + trap_el2_reg, reset_el2_val, HSTR_EL2, 0 },
> + /* HACR_EL2 */
> + { Op0(0b11), Op1(0b100), CRn(0b0001), CRm(0b0001), Op2(0b111),
> + trap_el2_reg, reset_el2_val, HACR_EL2, 0 },
> +
> + /* TTBR0_EL2 */
> + { Op0(0b11), Op1(0b100), CRn(0b0010), CRm(0b0000), Op2(0b000),
> + trap_el2_reg, reset_el2_val, TTBR0_EL2, 0 },
> + /* TCR_EL2 */
> + { Op0(0b11), Op1(0b100), CRn(0b0010), CRm(0b0000), Op2(0b010),
> + trap_el2_reg, reset_el2_val, TCR_EL2, 0 },
> + /* VTTBR_EL2 */
> + { Op0(0b11), Op1(0b100), CRn(0b0010), CRm(0b0001), Op2(0b000),
> + trap_el2_reg, reset_el2_val, VTTBR_EL2, 0 },
> + /* VTCR_EL2 */
> + { Op0(0b11), Op1(0b100), CRn(0b0010), CRm(0b0001), Op2(0b010),
> + trap_el2_reg, reset_el2_val, VTCR_EL2, 0 },
> +
> /* DACR32_EL2 */
> { Op0(0b11), Op1(0b100), CRn(0b0011), CRm(0b0000), Op2(0b000),
> NULL, reset_unknown, DACR32_EL2 },
> +
> + /* SPSR_EL2 */
> + { Op0(0b11), Op1(0b100), CRn(0b0100), CRm(0b0000), Op2(0b000),
> + trap_el2_reg, reset_el2_val, SPSR_EL2, 0 },
> + /* ELR_EL2 */
> + { Op0(0b11), Op1(0b100), CRn(0b0100), CRm(0b0000), Op2(0b001),
> + trap_el2_reg, reset_el2_val, ELR_EL2, 0 },
> + /* SP_EL1 */
> + { Op0(0b11), Op1(0b100), CRn(0b0100), CRm(0b0001), Op2(0b000),
> + trap_el2_reg },
> +
> /* IFSR32_EL2 */
> { Op0(0b11), Op1(0b100), CRn(0b0101), CRm(0b0000), Op2(0b001),
> NULL, reset_unknown, IFSR32_EL2 },
> + /* AFSR0_EL2 */
> + { Op0(0b11), Op1(0b100), CRn(0b0101), CRm(0b0001), Op2(0b000),
> + trap_el2_reg, reset_el2_val, AFSR0_EL2, 0 },
> + /* AFSR1_EL2 */
> + { Op0(0b11), Op1(0b100), CRn(0b0101), CRm(0b0001), Op2(0b001),
> + trap_el2_reg, reset_el2_val, AFSR1_EL2, 0 },
> + /* ESR_EL2 */
> + { Op0(0b11), Op1(0b100), CRn(0b0101), CRm(0b0010), Op2(0b000),
> + trap_el2_reg, reset_el2_val, ESR_EL2, 0 },
> /* FPEXC32_EL2 */
> { Op0(0b11), Op1(0b100), CRn(0b0101), CRm(0b0011), Op2(0b000),
> NULL, reset_val, FPEXC32_EL2, 0x70 },
> +
> + /* FAR_EL2 */
> + { Op0(0b11), Op1(0b100), CRn(0b0110), CRm(0b0000), Op2(0b000),
> + trap_el2_reg, reset_el2_val, FAR_EL2, 0 },
> + /* HPFAR_EL2 */
> + { Op0(0b11), Op1(0b100), CRn(0b0110), CRm(0b0000), Op2(0b100),
> + trap_el2_reg, reset_el2_val, HPFAR_EL2, 0 },
> +
> + /* MAIR_EL2 */
> + { Op0(0b11), Op1(0b100), CRn(0b1010), CRm(0b0010), Op2(0b000),
> + trap_el2_reg, reset_el2_val, MAIR_EL2, 0 },
> + /* AMAIR_EL2 */
> + { Op0(0b11), Op1(0b100), CRn(0b1010), CRm(0b0011), Op2(0b000),
> + trap_el2_reg, reset_el2_val, AMAIR_EL2, 0 },
> +
> + /* VBAR_EL2 */
> + { Op0(0b11), Op1(0b100), CRn(0b1100), CRm(0b0000), Op2(0b000),
> + trap_el2_reg, reset_el2_val, VBAR_EL2, 0 },
> + /* RVBAR_EL2 */
> + { Op0(0b11), Op1(0b100), CRn(0b1100), CRm(0b0000), Op2(0b001),
> + trap_el2_reg, reset_el2_val, RVBAR_EL2, 0 },
> + /* RMR_EL2 */
> + { Op0(0b11), Op1(0b100), CRn(0b1100), CRm(0b0000), Op2(0b010),
> + trap_el2_reg, reset_el2_val, RMR_EL2, 0 },
> +
> + /* TPIDR_EL2 */
> + { Op0(0b11), Op1(0b100), CRn(0b1101), CRm(0b0000), Op2(0b010),
> + trap_el2_reg, reset_el2_val, TPIDR_EL2, 0 },
> +
> + /* CNTVOFF_EL2 */
> + { Op0(0b11), Op1(0b100), CRn(0b1110), CRm(0b0000), Op2(0b011),
> + trap_el2_reg, reset_el2_val, CNTVOFF_EL2, 0 },
> + /* CNTHCTL_EL2 */
> + { Op0(0b11), Op1(0b100), CRn(0b1110), CRm(0b0001), Op2(0b000),
> + trap_el2_reg, reset_el2_val, CNTHCTL_EL2, 0 },
> + /* CNTHP_TVAL_EL2 */
> + { Op0(0b11), Op1(0b100), CRn(0b1110), CRm(0b0010), Op2(0b000),
> + trap_el2_reg, reset_el2_val, CNTHP_TVAL_EL2, 0 },
> + /* CNTHP_CTL_EL2 */
> + { Op0(0b11), Op1(0b100), CRn(0b1110), CRm(0b0010), Op2(0b001),
> + trap_el2_reg, reset_el2_val, CNTHP_CTL_EL2, 0 },
> + /* CNTHP_CVAL_EL2 */
> + { Op0(0b11), Op1(0b100), CRn(0b1110), CRm(0b0010), Op2(0b010),
> + trap_el2_reg, reset_el2_val, CNTHP_CVAL_EL2, 0 },
> +
> };
>
> static bool trap_dbgidr(struct kvm_vcpu *vcpu,
> diff --git a/arch/arm64/kvm/sys_regs.h b/arch/arm64/kvm/sys_regs.h
> index dbbb01c..181290f 100644
> --- a/arch/arm64/kvm/sys_regs.h
> +++ b/arch/arm64/kvm/sys_regs.h
> @@ -117,6 +117,13 @@ static inline void reset_val(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r
> vcpu_sys_reg(vcpu, r->reg) = r->val;
> }
>
> +static inline void reset_el2_val(struct kvm_vcpu *vcpu,
> + const struct sys_reg_desc *r)
> +{
> + BUG_ON(r->reg >= NR_EL2_REGS);
> + vcpu_el2_reg(vcpu, r->reg) = r->val;
> +}
> +
> static inline int cmp_sys_reg(const struct sys_reg_desc *i1,
> const struct sys_reg_desc *i2)
> {
> --
> 1.9.1
>
>

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