Re: [PATCH 07/59] KVM: arm64: nv: Add EL2 system registers to vcpu context

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On 6/21/19 10:37 AM, Marc Zyngier wrote:
> From: Jintack Lim <jintack.lim@xxxxxxxxxx>
>
> 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 the following instructions in EL1 will trap to EL2:
> tlbi, at, eret, and msr/mrs instructions to access SP_EL1. Most of the
> instructions that trap to EL2 with the NV bit were undef at EL1 prior to
> ARM v8.3. The only instruction that was not undef is eret.
>
> This patch sets up a handler for EL2 registers and SP_EL1 register
> accesses at EL1. The host hypervisor keeps those register values in
> memory, and will emulate their behavior.
>
> This patch doesn't set the NV bit yet. It will be set in a later patch
> once nested virtualization support is completed.
>
> Signed-off-by: Jintack Lim <jintack.lim@xxxxxxxxxx>
> Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
> ---
>  arch/arm64/include/asm/kvm_host.h | 37 +++++++++++++++-
>  arch/arm64/include/asm/sysreg.h   | 50 ++++++++++++++++++++-
>  arch/arm64/kvm/sys_regs.c         | 74 ++++++++++++++++++++++++++++---
>  3 files changed, 154 insertions(+), 7 deletions(-)
>
> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> index 4bcd9c1291d5..2d4290d2513a 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -173,12 +173,47 @@ enum vcpu_sysreg {
>  	APGAKEYLO_EL1,
>  	APGAKEYHI_EL1,
>  
> -	/* 32bit specific registers. Keep them at the end of the range */
> +	/* 32bit specific registers. */
>  	DACR32_EL2,	/* Domain Access Control Register */
>  	IFSR32_EL2,	/* Instruction Fault Status Register */
>  	FPEXC32_EL2,	/* Floating-Point Exception Control Register */
>  	DBGVCR32_EL2,	/* Debug Vector Catch Register */
>  
> +	/* EL2 registers sorted ascending by Op0, Op1, CRn, CRm, Op2 */
> +	FIRST_EL2_SYSREG,
> +	VPIDR_EL2 = FIRST_EL2_SYSREG,
> +			/* Virtualization Processor ID Register */
> +	VMPIDR_EL2,	/* Virtualization Multiprocessor ID Register */
> +	SCTLR_EL2,	/* System Control Register (EL2) */
> +	ACTLR_EL2,	/* Auxiliary Control Register (EL2) */
> +	HCR_EL2,	/* Hypervisor Configuration Register */
> +	MDCR_EL2,	/* Monitor Debug Configuration Register (EL2) */
> +	CPTR_EL2,	/* Architectural Feature Trap Register (EL2) */
> +	HSTR_EL2,	/* Hypervisor System Trap Register */
> +	HACR_EL2,	/* Hypervisor Auxiliary Control Register */
> +	TTBR0_EL2,	/* Translation Table Base Register 0 (EL2) */
> +	TTBR1_EL2,	/* Translation Table Base Register 1 (EL2) */
> +	TCR_EL2,	/* Translation Control Register (EL2) */
> +	VTTBR_EL2,	/* Virtualization Translation Table Base Register */
> +	VTCR_EL2,	/* Virtualization Translation Control Register */
> +	SPSR_EL2,	/* EL2 saved program status register */
> +	ELR_EL2,	/* EL2 exception link register */
> +	AFSR0_EL2,	/* Auxiliary Fault Status Register 0 (EL2) */
> +	AFSR1_EL2,	/* Auxiliary Fault Status Register 1 (EL2) */
> +	ESR_EL2,	/* Exception Syndrome Register (EL2) */
> +	FAR_EL2,	/* Hypervisor IPA Fault Address Register */
> +	HPFAR_EL2,	/* Hypervisor IPA Fault Address Register */
> +	MAIR_EL2,	/* Memory Attribute Indirection Register (EL2) */
> +	AMAIR_EL2,	/* Auxiliary Memory Attribute Indirection Register (EL2) */
> +	VBAR_EL2,	/* Vector Base Address Register (EL2) */
> +	RVBAR_EL2,	/* Reset Vector Base Address Register */
> +	RMR_EL2,	/* Reset Management Register */
> +	CONTEXTIDR_EL2,	/* Context ID Register (EL2) */
> +	TPIDR_EL2,	/* EL2 Software Thread ID Register */
> +	CNTVOFF_EL2,	/* Counter-timer Virtual Offset register */
> +	CNTHCTL_EL2,	/* Counter-timer Hypervisor Control register */
> +	SP_EL2,		/* EL2 Stack Pointer */
> +
>  	NR_SYS_REGS	/* Nothing after this line! */
>  };
>  
> diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
> index f3ca7e4796ab..8b95f2c42c3d 100644
> --- a/arch/arm64/include/asm/sysreg.h
> +++ b/arch/arm64/include/asm/sysreg.h
> @@ -411,17 +411,49 @@
>  
>  #define SYS_PMCCFILTR_EL0		sys_reg(3, 3, 14, 15, 7)
>  
> +#define SYS_VPIDR_EL2			sys_reg(3, 4, 0, 0, 0)
> +#define SYS_VMPIDR_EL2			sys_reg(3, 4, 0, 0, 5)
> +
> +#define SYS_SCTLR_EL2			sys_reg(3, 4, 1, 0, 0)
> +#define SYS_ACTLR_EL2			sys_reg(3, 4, 1, 0, 1)
> +#define SYS_HCR_EL2			sys_reg(3, 4, 1, 1, 0)
> +#define SYS_MDCR_EL2			sys_reg(3, 4, 1, 1, 1)
> +#define SYS_CPTR_EL2			sys_reg(3, 4, 1, 1, 2)
> +#define SYS_HSTR_EL2			sys_reg(3, 4, 1, 1, 3)
> +#define SYS_HACR_EL2			sys_reg(3, 4, 1, 1, 7)
> +
>  #define SYS_ZCR_EL2			sys_reg(3, 4, 1, 2, 0)
> +
> +#define SYS_TTBR0_EL2			sys_reg(3, 4, 2, 0, 0)
> +#define SYS_TTBR1_EL2			sys_reg(3, 4, 2, 0, 1)
> +#define SYS_TCR_EL2			sys_reg(3, 4, 2, 0, 2)
> +#define SYS_VTTBR_EL2			sys_reg(3, 4, 2, 1, 0)
> +#define SYS_VTCR_EL2			sys_reg(3, 4, 2, 1, 2)
> +
>  #define SYS_DACR32_EL2			sys_reg(3, 4, 3, 0, 0)
> +
>  #define SYS_SPSR_EL2			sys_reg(3, 4, 4, 0, 0)
>  #define SYS_ELR_EL2			sys_reg(3, 4, 4, 0, 1)
> +#define SYS_SP_EL1			sys_reg(3, 4, 4, 1, 0)
> +
>  #define SYS_IFSR32_EL2			sys_reg(3, 4, 5, 0, 1)
> +#define SYS_AFSR0_EL2			sys_reg(3, 4, 5, 1, 0)
> +#define SYS_AFSR1_EL2			sys_reg(3, 4, 5, 1, 1)
>  #define SYS_ESR_EL2			sys_reg(3, 4, 5, 2, 0)
>  #define SYS_VSESR_EL2			sys_reg(3, 4, 5, 2, 3)
>  #define SYS_FPEXC32_EL2			sys_reg(3, 4, 5, 3, 0)
>  #define SYS_FAR_EL2			sys_reg(3, 4, 6, 0, 0)
>  
> -#define SYS_VDISR_EL2			sys_reg(3, 4, 12, 1,  1)
> +#define SYS_FAR_EL2			sys_reg(3, 4, 6, 0, 0)
> +#define SYS_HPFAR_EL2			sys_reg(3, 4, 6, 0, 4)
> +
> +#define SYS_MAIR_EL2			sys_reg(3, 4, 10, 2, 0)
> +#define SYS_AMAIR_EL2			sys_reg(3, 4, 10, 3, 0)
> +
> +#define SYS_VBAR_EL2			sys_reg(3, 4, 12, 0, 0)
> +#define SYS_RVBAR_EL2			sys_reg(3, 4, 12, 0, 1)
> +#define SYS_RMR_EL2			sys_reg(3, 4, 12, 0, 2)
> +#define SYS_VDISR_EL2			sys_reg(3, 4, 12, 1, 1)
>  #define __SYS__AP0Rx_EL2(x)		sys_reg(3, 4, 12, 8, x)
>  #define SYS_ICH_AP0R0_EL2		__SYS__AP0Rx_EL2(0)
>  #define SYS_ICH_AP0R1_EL2		__SYS__AP0Rx_EL2(1)
> @@ -463,23 +495,37 @@
>  #define SYS_ICH_LR14_EL2		__SYS__LR8_EL2(6)
>  #define SYS_ICH_LR15_EL2		__SYS__LR8_EL2(7)
>  
> +#define SYS_CONTEXTIDR_EL2		sys_reg(3, 4, 13, 0, 1)
> +#define SYS_TPIDR_EL2			sys_reg(3, 4, 13, 0, 2)
> +
> +#define SYS_CNTVOFF_EL2			sys_reg(3, 4, 14, 0, 3)
> +#define SYS_CNTHCTL_EL2			sys_reg(3, 4, 14, 1, 0)
> +
>  /* VHE encodings for architectural EL0/1 system registers */
>  #define SYS_SCTLR_EL12			sys_reg(3, 5, 1, 0, 0)
>  #define SYS_CPACR_EL12			sys_reg(3, 5, 1, 0, 2)
>  #define SYS_ZCR_EL12			sys_reg(3, 5, 1, 2, 0)
> +
>  #define SYS_TTBR0_EL12			sys_reg(3, 5, 2, 0, 0)
>  #define SYS_TTBR1_EL12			sys_reg(3, 5, 2, 0, 1)
>  #define SYS_TCR_EL12			sys_reg(3, 5, 2, 0, 2)
> +
>  #define SYS_SPSR_EL12			sys_reg(3, 5, 4, 0, 0)
>  #define SYS_ELR_EL12			sys_reg(3, 5, 4, 0, 1)
> +
>  #define SYS_AFSR0_EL12			sys_reg(3, 5, 5, 1, 0)
>  #define SYS_AFSR1_EL12			sys_reg(3, 5, 5, 1, 1)
>  #define SYS_ESR_EL12			sys_reg(3, 5, 5, 2, 0)
> +
>  #define SYS_FAR_EL12			sys_reg(3, 5, 6, 0, 0)
> +
>  #define SYS_MAIR_EL12			sys_reg(3, 5, 10, 2, 0)
>  #define SYS_AMAIR_EL12			sys_reg(3, 5, 10, 3, 0)
> +
>  #define SYS_VBAR_EL12			sys_reg(3, 5, 12, 0, 0)
> +
>  #define SYS_CONTEXTIDR_EL12		sys_reg(3, 5, 13, 0, 1)
> +
>  #define SYS_CNTKCTL_EL12		sys_reg(3, 5, 14, 1, 0)
>  #define SYS_CNTP_TVAL_EL02		sys_reg(3, 5, 14, 2, 0)
>  #define SYS_CNTP_CTL_EL02		sys_reg(3, 5, 14, 2, 1)
> @@ -488,6 +534,8 @@
>  #define SYS_CNTV_CTL_EL02		sys_reg(3, 5, 14, 3, 1)
>  #define SYS_CNTV_CVAL_EL02		sys_reg(3, 5, 14, 3, 2)
>  
> +#define SYS_SP_EL2			sys_reg(3, 6,  4, 1, 0)
> +
>  /* Common SCTLR_ELx flags. */
>  #define SCTLR_ELx_DSSBS	(_BITUL(44))
>  #define SCTLR_ELx_ENIA	(_BITUL(31))
> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> index adb8a7e9c8e4..e81be6debe07 100644
> --- a/arch/arm64/kvm/sys_regs.c
> +++ b/arch/arm64/kvm/sys_regs.c
> @@ -184,6 +184,18 @@ static u32 get_ccsidr(u32 csselr)
>  	return ccsidr;
>  }
>  
> +static bool access_rw(struct kvm_vcpu *vcpu,
> +		      struct sys_reg_params *p,
> +		      const struct sys_reg_desc *r)
> +{
> +	if (p->is_write)
> +		vcpu_write_sys_reg(vcpu, p->regval, r->reg);
> +	else
> +		p->regval = vcpu_read_sys_reg(vcpu, r->reg);
> +
> +	return true;
> +}
> +
>  /*
>   * See note at ARMv7 ARM B1.14.4 (TL;DR: S/W ops are not easily virtualized).
>   */
> @@ -394,12 +406,9 @@ static bool trap_debug_regs(struct kvm_vcpu *vcpu,
>  			    struct sys_reg_params *p,
>  			    const struct sys_reg_desc *r)
>  {
> -	if (p->is_write) {
> -		vcpu_write_sys_reg(vcpu, p->regval, r->reg);
> +	access_rw(vcpu, p, r);
> +	if (p->is_write)
>  		vcpu->arch.flags |= KVM_ARM64_DEBUG_DIRTY;
> -	} else {
> -		p->regval = vcpu_read_sys_reg(vcpu, r->reg);
> -	}
>  
>  	trace_trap_reg(__func__, r->reg, p->is_write, p->regval);
>  
> @@ -1354,6 +1363,19 @@ static bool access_ccsidr(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
>  	.set_user = set_raz_id_reg,		\
>  }
>  
> +static bool access_sp_el1(struct kvm_vcpu *vcpu,
> +			  struct sys_reg_params *p,
> +			  const struct sys_reg_desc *r)
> +{
> +	/* SP_EL1 is NOT maintained in sys_regs array */
> +	if (p->is_write)
> +		vcpu->arch.ctxt.gp_regs.sp_el1 = p->regval;
> +	else
> +		p->regval = vcpu->arch.ctxt.gp_regs.sp_el1;
> +
> +	return true;
> +}
> +
>  /*
>   * Architected system registers.
>   * Important: Must be sorted ascending by Op0, Op1, CRn, CRm, Op2
> @@ -1646,9 +1668,51 @@ static const struct sys_reg_desc sys_reg_descs[] = {
>  	 */
>  	{ SYS_DESC(SYS_PMCCFILTR_EL0), access_pmu_evtyper, reset_val, PMCCFILTR_EL0, 0 },
I have to admit I haven't gone through all the patches, or maybe this is part of
the bits that will be added at a later date, but some of the reset values seem
incorrect according to ARM DDI 0487D.a. I'll comment below the relevant registers.
>  
> +	{ SYS_DESC(SYS_VPIDR_EL2), access_rw, reset_val, VPIDR_EL2, 0 },
> +	{ SYS_DESC(SYS_VMPIDR_EL2), access_rw, reset_val, VMPIDR_EL2, 0 },
> +
> +	{ SYS_DESC(SYS_SCTLR_EL2), access_rw, reset_val, SCTLR_EL2, 0 },
Some bits are RES1 for SCTLR_EL2.
> +	{ SYS_DESC(SYS_ACTLR_EL2), access_rw, reset_val, ACTLR_EL2, 0 },
> +	{ SYS_DESC(SYS_HCR_EL2), access_rw, reset_val, HCR_EL2, 0 },
> +	{ SYS_DESC(SYS_MDCR_EL2), access_rw, reset_val, MDCR_EL2, 0 },
> +	{ SYS_DESC(SYS_CPTR_EL2), access_rw, reset_val, CPTR_EL2, 0 },
Some bits are RES1 for CPTR_EL2 if HCR_EL2.E2H == 0, which the reset value for
HCR_EL2 seems to imply.
> +	{ SYS_DESC(SYS_HSTR_EL2), access_rw, reset_val, HSTR_EL2, 0 },
> +	{ SYS_DESC(SYS_HACR_EL2), access_rw, reset_val, HACR_EL2, 0 },
> +
> +	{ SYS_DESC(SYS_TTBR0_EL2), access_rw, reset_val, TTBR0_EL2, 0 },
> +	{ SYS_DESC(SYS_TTBR1_EL2), access_rw, reset_val, TTBR1_EL2, 0 },
> +	{ SYS_DESC(SYS_TCR_EL2), access_rw, reset_val, TCR_EL2, 0 },
Same here, bits 31 and 23 are RES1 for TCR_EL2 when HCR_EL2.E2H == 0.
> +	{ SYS_DESC(SYS_VTTBR_EL2), access_rw, reset_val, VTTBR_EL2, 0 },
> +	{ SYS_DESC(SYS_VTCR_EL2), access_rw, reset_val, VTCR_EL2, 0 },
> +
>  	{ SYS_DESC(SYS_DACR32_EL2), NULL, reset_unknown, DACR32_EL2 },
> +	{ SYS_DESC(SYS_SPSR_EL2), access_rw, reset_val, SPSR_EL2, 0 },
> +	{ SYS_DESC(SYS_ELR_EL2), access_rw, reset_val, ELR_EL2, 0 },
> +	{ SYS_DESC(SYS_SP_EL1), access_sp_el1},
> +
>  	{ SYS_DESC(SYS_IFSR32_EL2), NULL, reset_unknown, IFSR32_EL2 },
> +	{ SYS_DESC(SYS_AFSR0_EL2), access_rw, reset_val, AFSR0_EL2, 0 },
> +	{ SYS_DESC(SYS_AFSR1_EL2), access_rw, reset_val, AFSR1_EL2, 0 },
> +	{ SYS_DESC(SYS_ESR_EL2), access_rw, reset_val, ESR_EL2, 0 },
>  	{ SYS_DESC(SYS_FPEXC32_EL2), NULL, reset_val, FPEXC32_EL2, 0x700 },
> +
> +	{ SYS_DESC(SYS_FAR_EL2), access_rw, reset_val, FAR_EL2, 0 },
> +	{ SYS_DESC(SYS_HPFAR_EL2), access_rw, reset_val, HPFAR_EL2, 0 },
> +
> +	{ SYS_DESC(SYS_MAIR_EL2), access_rw, reset_val, MAIR_EL2, 0 },
> +	{ SYS_DESC(SYS_AMAIR_EL2), access_rw, reset_val, AMAIR_EL2, 0 },
> +
> +	{ SYS_DESC(SYS_VBAR_EL2), access_rw, reset_val, VBAR_EL2, 0 },
> +	{ SYS_DESC(SYS_RVBAR_EL2), access_rw, reset_val, RVBAR_EL2, 0 },
> +	{ SYS_DESC(SYS_RMR_EL2), access_rw, reset_val, RMR_EL2, 0 },
Bit AA64 [0] for RMR_EL2 is RAO/WI for EL2 cannot aarch32, which is what the
patches seem to enforce.
> +
> +	{ SYS_DESC(SYS_CONTEXTIDR_EL2), access_rw, reset_val, CONTEXTIDR_EL2, 0 },
> +	{ SYS_DESC(SYS_TPIDR_EL2), access_rw, reset_val, TPIDR_EL2, 0 },
> +
> +	{ SYS_DESC(SYS_CNTVOFF_EL2), access_rw, reset_val, CNTVOFF_EL2, 0 },
> +	{ SYS_DESC(SYS_CNTHCTL_EL2), access_rw, reset_val, CNTHCTL_EL2, 0 },
> +
> +	{ SYS_DESC(SYS_SP_EL2), NULL, reset_unknown, SP_EL2 },
>  };
>  
>  static bool trap_dbgidr(struct kvm_vcpu *vcpu,
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