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Subject[RFC 12/55] KVM: arm64: Handle EL2 register access traps
Date
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 -
tlbi and at instructions which are undefined when exectued in EL1, eret
instruction, msr/mrs instructions to access SP_EL1.

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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