Subject: [PATCH v3 26/32] arm64: KVM: 32bit handling of coprocessor traps

From: [email-masked] (Christoffer Dall)
Date: Tue, 23 Apr 2013 16:01:59 -0700

On Mon, Apr 08, 2013 at 05:17:28PM +0100, Marc Zyngier wrote:
> Provide the necessary infrastructure to trap coprocessor accesses that
> occur when running 32bit guests.
> 
> Also wire SMC and HVC trapped in 32bit mode while were at it.
> 
> Reviewed-by: Christopher Covington <[email-masked]>
> Signed-off-by: Marc Zyngier <[email-masked]>
> ---
>  arch/arm64/include/asm/kvm_coproc.h |   5 +
>  arch/arm64/kvm/handle_exit.c        |   7 ++
>  arch/arm64/kvm/sys_regs.c           | 178 ++++++++++++++++++++++++++++++++++--
>  3 files changed, 183 insertions(+), 7 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/kvm_coproc.h b/arch/arm64/include/asm/kvm_coproc.h
> index 9b4477a..9a59301 100644
> --- a/arch/arm64/include/asm/kvm_coproc.h
> +++ b/arch/arm64/include/asm/kvm_coproc.h
> @@ -32,11 +32,16 @@ struct kvm_sys_reg_table {
>  
>  struct kvm_sys_reg_target_table {
>  	struct kvm_sys_reg_table table64;
> +	struct kvm_sys_reg_table table32;
>  };
>  
>  void kvm_register_target_sys_reg_table(unsigned int target,
>  				       struct kvm_sys_reg_target_table *table);
>  
> +int kvm_handle_cp14_load_store(struct kvm_vcpu *vcpu, struct kvm_run *run);
> +int kvm_handle_cp14_access(struct kvm_vcpu *vcpu, struct kvm_run *run);
> +int kvm_handle_cp15_32(struct kvm_vcpu *vcpu, struct kvm_run *run);
> +int kvm_handle_cp15_64(struct kvm_vcpu *vcpu, struct kvm_run *run);
>  int kvm_handle_sys_reg(struct kvm_vcpu *vcpu, struct kvm_run *run);
>  
>  #define kvm_coproc_table_init kvm_sys_reg_table_init
> diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c
> index 4766b7f..9beaca03 100644
> --- a/arch/arm64/kvm/handle_exit.c
> +++ b/arch/arm64/kvm/handle_exit.c
> @@ -62,6 +62,13 @@ static int kvm_handle_wfi(struct kvm_vcpu *vcpu, struct kvm_run *run)
>  
>  static exit_handle_fn arm_exit_handlers[] = {
>  	[ESR_EL2_EC_WFI]	= kvm_handle_wfi,
> +	[ESR_EL2_EC_CP15_32]	= kvm_handle_cp15_32,
> +	[ESR_EL2_EC_CP15_64]	= kvm_handle_cp15_64,
> +	[ESR_EL2_EC_CP14_MR]	= kvm_handle_cp14_access,
> +	[ESR_EL2_EC_CP14_LS]	= kvm_handle_cp14_load_store,
> +	[ESR_EL2_EC_CP14_64]	= kvm_handle_cp14_access,
> +	[ESR_EL2_EC_HVC32]	= handle_hvc,
> +	[ESR_EL2_EC_SMC32]	= handle_smc,
>  	[ESR_EL2_EC_HVC64]	= handle_hvc,
>  	[ESR_EL2_EC_SMC64]	= handle_smc,
>  	[ESR_EL2_EC_SYS64]	= kvm_handle_sys_reg,
> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> index 9df3b32..0303218 100644
> --- a/arch/arm64/kvm/sys_regs.c
> +++ b/arch/arm64/kvm/sys_regs.c
> @@ -38,6 +38,10 @@
>   * types are different. My gut feeling is that it should be pretty
>   * easy to merge, but that would be an ABI breakage -- again. VFP
>   * would also need to be abstracted.
> + *
> + * For AArch32, we only take care of what is being trapped. Anything
> + * that has to do with init and userspace access has to go via the
> + * 64bit interface.
>   */
>  
>  /* 3 bits per cache level, as per CLIDR, but non-existent caches always 0 */
> @@ -163,6 +167,16 @@ static const struct sys_reg_desc sys_reg_descs[] = {
>  	{ Op0(0b01), Op1(0b000), CRn(0b0111), CRm(0b1110), Op2(0b010),
>  	  access_dcsw },
>  
> +	/* TEECR32_EL1 */
> +	{ Op0(0b10), Op1(0b010), CRn(0b0000), CRm(0b0000), Op2(0b000),
> +	  NULL, reset_val, TEECR32_EL1, 0 },
> +	/* TEEHBR32_EL1 */
> +	{ Op0(0b10), Op1(0b010), CRn(0b0001), CRm(0b0000), Op2(0b000),
> +	  NULL, reset_val, TEEHBR32_EL1, 0 },
> +	/* DBGVCR32_EL2 */
> +	{ Op0(0b10), Op1(0b100), CRn(0b0000), CRm(0b0111), Op2(0b000),
> +	  NULL, reset_val, DBGVCR32_EL2, 0 },
> +
>  	/* MPIDR_EL1 */
>  	{ Op0(0b11), Op1(0b000), CRn(0b0000), CRm(0b0000), Op2(0b101),
>  	  NULL, reset_mpidr, MPIDR_EL1 },
> @@ -273,6 +287,39 @@ static const struct sys_reg_desc sys_reg_descs[] = {
>  	/* TPIDRRO_EL0 */
>  	{ Op0(0b11), Op1(0b011), CRn(0b1101), CRm(0b0000), Op2(0b011),
>  	  NULL, reset_unknown, TPIDRRO_EL0 },
> +
> +	/* DACR32_EL2 */
> +	{ Op0(0b11), Op1(0b100), CRn(0b0011), CRm(0b0000), Op2(0b000),
> +	  NULL, reset_unknown, DACR32_EL2 },
> +	/* IFSR32_EL2 */
> +	{ Op0(0b11), Op1(0b100), CRn(0b0101), CRm(0b0000), Op2(0b001),
> +	  NULL, reset_unknown, IFSR32_EL2 },
> +	/* FPEXC32_EL2 */
> +	{ Op0(0b11), Op1(0b100), CRn(0b0101), CRm(0b0011), Op2(0b000),
> +	  NULL, reset_val, FPEXC32_EL2, 0x70 },
> +};
> +
> +/* Trapped cp15 registers */
> +static const struct sys_reg_desc cp15_regs[] = {
> +	/*
> +	 * DC{C,I,CI}SW operations:
> +	 */
> +	{ Op1( 0), CRn( 7), CRm( 6), Op2( 2), access_dcsw },
> +	{ Op1( 0), CRn( 7), CRm(10), Op2( 2), access_dcsw },
> +	{ Op1( 0), CRn( 7), CRm(14), Op2( 2), access_dcsw },
> +	{ Op1( 0), CRn( 9), CRm(12), Op2( 0), pm_fake },
> +	{ Op1( 0), CRn( 9), CRm(12), Op2( 1), pm_fake },
> +	{ Op1( 0), CRn( 9), CRm(12), Op2( 2), pm_fake },
> +	{ Op1( 0), CRn( 9), CRm(12), Op2( 3), pm_fake },
> +	{ Op1( 0), CRn( 9), CRm(12), Op2( 5), pm_fake },
> +	{ Op1( 0), CRn( 9), CRm(12), Op2( 6), pm_fake },
> +	{ Op1( 0), CRn( 9), CRm(12), Op2( 7), pm_fake },
> +	{ Op1( 0), CRn( 9), CRm(13), Op2( 0), pm_fake },
> +	{ Op1( 0), CRn( 9), CRm(13), Op2( 1), pm_fake },
> +	{ Op1( 0), CRn( 9), CRm(13), Op2( 2), pm_fake },
> +	{ Op1( 0), CRn( 9), CRm(14), Op2( 0), pm_fake },
> +	{ Op1( 0), CRn( 9), CRm(14), Op2( 1), pm_fake },
> +	{ Op1( 0), CRn( 9), CRm(14), Op2( 2), pm_fake },
>  };
>  
>  /* Target specific emulation tables */
> @@ -285,13 +332,20 @@ void kvm_register_target_sys_reg_table(unsigned int target,
>  }
>  
>  /* Get specific register table for this target. */
> -static const struct sys_reg_desc *get_target_table(unsigned target, size_t *num)
> +static const struct sys_reg_desc *get_target_table(unsigned target,
> +						   bool mode_is_64,
> +						   size_t *num)
>  {
>  	struct kvm_sys_reg_target_table *table;
>  
>  	table = target_tables[target];
> -	*num = table->table64.num;
> -	return table->table64.table;
> +	if (mode_is_64) {
> +		*num = table->table64.num;
> +		return table->table64.table;
> +	} else {
> +		*num = table->table32.num;
> +		return table->table32.table;
> +	}
>  }
>  
>  static const struct sys_reg_desc *find_reg(const struct sys_reg_params *params,
> @@ -319,13 +373,123 @@ static const struct sys_reg_desc *find_reg(const struct sys_reg_params *params,
>  	return NULL;
>  }
>  
> +int kvm_handle_cp14_load_store(struct kvm_vcpu *vcpu, struct kvm_run *run)
> +{
> +	kvm_inject_undefined(vcpu);
> +	return 1;
> +}
> +
> +int kvm_handle_cp14_access(struct kvm_vcpu *vcpu, struct kvm_run *run)
> +{
> +	kvm_inject_undefined(vcpu);
> +	return 1;
> +}
> +
> +static int emulate_cp15(struct kvm_vcpu *vcpu,
> +			const struct sys_reg_params *params)
> +{
> +	size_t num;
> +	const struct sys_reg_desc *table, *r;
> +
> +	table = get_target_table(vcpu->arch.target, false, &num);
> +
> +	/* Search target-specific then generic table. */
> +	r = find_reg(params, table, num);
> +	if (!r)
> +		r = find_reg(params, cp15_regs, ARRAY_SIZE(cp15_regs));
> +
> +	if (likely(r)) {
> +		/* If we don't have an accessor, we should never get here! */
> +		BUG_ON(!r->access);

again not quite sure if this warrants a crash of the entire host.

> +
> +		if (likely(r->access(vcpu, params, r))) {
> +			/* Skip instruction, since it was emulated */
> +			kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));
> +			return 1;
> +		}
> +		/* If access function fails, it should complain. */
> +	} else {
> +		kvm_err("Unsupported guest CP15 access at: %08lx\n",
> +			*vcpu_pc(vcpu));
> +		print_sys_reg_instr(params);
> +	}
> +	kvm_inject_undefined(vcpu);
> +	return 1;
> +}
> +
> +/**
> + * kvm_handle_cp15_64 -- handles a mrrc/mcrr trap on a guest CP15 access
> + * @vcpu: The VCPU pointer
> + * @run:  The kvm_run struct
> + */
> +int kvm_handle_cp15_64(struct kvm_vcpu *vcpu, struct kvm_run *run)
> +{
> +	struct sys_reg_params params;
> +	u32 hsr = kvm_vcpu_get_hsr(vcpu);
> +	int Rt2 = (hsr >> 10) & 0xf;
> +	int ret;
> +
> +	params.CRm = (hsr >> 1) & 0xf;
> +	params.Rt = (hsr >> 5) & 0xf;
> +	params.is_write = ((hsr & 1) == 0);
> +
> +	params.Op0 = 0;
> +	params.Op1 = (hsr >> 16) & 0xf;
> +	params.Op2 = 0;
> +	params.CRn = 0;
> +
> +	/*
> +	 * Massive hack here. Store Rt2 in the top 32bits so we only
> +	 * have one register to deal with. As we use the same trap
> +	 * backends between AArch32 and AArch64, we get away with it.
> +	 */
> +	if (params.is_write) {
> +		u64 val = *vcpu_reg(vcpu, params.Rt);
> +		val &= 0xffffffff;
> +		val |= *vcpu_reg(vcpu, Rt2) << 32;
> +		*vcpu_reg(vcpu, params.Rt) = val;
> +	}
> +
> +	ret = emulate_cp15(vcpu, &params);
> +
> +	/* Reverse hack here */

nit: consider changing the wording to something like 'Similar hack for
reads here', so readers don't think you are trying to reverse the hack
you did above.

> +	if (ret && !params.is_write) {
> +		u64 val = *vcpu_reg(vcpu, params.Rt);
> +		val >>= 32;
> +		*vcpu_reg(vcpu, Rt2) = val;

actually the emulate_cp15 should probably be turned into a void and the
ret check could go away, same thing on the 32-bit side.

> +	}
> +
> +	return ret;
> +}
> +
> +/**
> + * kvm_handle_cp15_32 -- handles a mrc/mcr trap on a guest CP15 access
> + * @vcpu: The VCPU pointer
> + * @run:  The kvm_run struct
> + */
> +int kvm_handle_cp15_32(struct kvm_vcpu *vcpu, struct kvm_run *run)
> +{
> +	struct sys_reg_params params;
> +	u32 hsr = kvm_vcpu_get_hsr(vcpu);
> +
> +	params.CRm = (hsr >> 1) & 0xf;
> +	params.Rt  = (hsr >> 5) & 0xf;
> +	params.is_write = ((hsr & 1) == 0);
> +	params.CRn = (hsr >> 10) & 0xf;
> +	params.Op0 = 0;
> +	params.Op1 = (hsr >> 14) & 0x7;
> +	params.Op2 = (hsr >> 17) & 0x7;
> +
> +	return emulate_cp15(vcpu, &params);
> +}
> +
>  static int emulate_sys_reg(struct kvm_vcpu *vcpu,
>  			   const struct sys_reg_params *params)
>  {
>  	size_t num;
>  	const struct sys_reg_desc *table, *r;
>  
> -	table = get_target_table(vcpu->arch.target, &num);
> +	table = get_target_table(vcpu->arch.target, true, &num);
>  
>  	/* Search target-specific then generic table. */
>  	r = find_reg(params, table, num);
> @@ -430,7 +594,7 @@ static const struct sys_reg_desc *index_to_sys_reg_desc(struct kvm_vcpu *vcpu,
>  	if (!index_to_params(id, &params))
>  		return NULL;
>  
> -	table = get_target_table(vcpu->arch.target, &num);
> +	table = get_target_table(vcpu->arch.target, true, &num);
>  	r = find_reg(&params, table, num);
>  	if (!r)
>  		r = find_reg(&params, sys_reg_descs, ARRAY_SIZE(sys_reg_descs));
> @@ -750,7 +914,7 @@ static int walk_sys_regs(struct kvm_vcpu *vcpu, u64 __user *uind)
>  	size_t num;
>  
>  	/* We check for duplicates here, to allow arch-specific overrides. */
> -	i1 = get_target_table(vcpu->arch.target, &num);
> +	i1 = get_target_table(vcpu->arch.target, true, &num);
>  	end1 = i1 + num;
>  	i2 = sys_reg_descs;
>  	end2 = sys_reg_descs + ARRAY_SIZE(sys_reg_descs);
> @@ -862,7 +1026,7 @@ void kvm_reset_sys_regs(struct kvm_vcpu *vcpu)
>  	/* Generic chip reset first (so target could override). */
>  	reset_sys_reg_descs(vcpu, sys_reg_descs, ARRAY_SIZE(sys_reg_descs));
>  
> -	table = get_target_table(vcpu->arch.target, &num);
> +	table = get_target_table(vcpu->arch.target, true, &num);
>  	reset_sys_reg_descs(vcpu, table, num);
>  
>  	for (num = 1; num < NR_SYS_REGS; num++)
> -- 
> 1.8.1.4
> 
> 
> 
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