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Commit 8c86dfe3 authored by Dave Martin's avatar Dave Martin Committed by Marc Zyngier
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KVM: arm64: Reject ioctl access to FPSIMD V-regs on SVE vcpus 



In order to avoid the pointless complexity of maintaining two ioctl
register access views of the same data, this patch blocks ioctl
access to the FPSIMD V-registers on vcpus that support SVE.

This will make it more straightforward to add SVE register access
support.

Since SVE is an opt-in feature for userspace, this will not affect
existing users.

Signed-off-by: default avatarDave Martin <Dave.Martin@arm.com>
Reviewed-by: default avatarJulien Thierry <julien.thierry@arm.com>
Tested-by: default avatarzhang.lei <zhang.lei@jp.fujitsu.com>
Signed-off-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
parent be25bbb3

arch/arm64/kvm/guest.c

+36 −12
Original line number Diff line number Diff line
@@ -54,12 +54,19 @@ int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu) 
	return 0;

}



static bool core_reg_offset_is_vreg(u64 off)

{

	return off >= KVM_REG_ARM_CORE_REG(fp_regs.vregs) &&

		off < KVM_REG_ARM_CORE_REG(fp_regs.fpsr);

}



static u64 core_reg_offset_from_id(u64 id)

{

	return id & ~(KVM_REG_ARCH_MASK | KVM_REG_SIZE_MASK | KVM_REG_ARM_CORE);

}



static int validate_core_offset(const struct kvm_one_reg *reg)

static int validate_core_offset(const struct kvm_vcpu *vcpu,

				const struct kvm_one_reg *reg)

{

	u64 off = core_reg_offset_from_id(reg->id);

	int size;
@@ -91,11 +98,19 @@ static int validate_core_offset(const struct kvm_one_reg *reg) 
		return -EINVAL;

	}



	if (KVM_REG_SIZE(reg->id) == size &&

	    IS_ALIGNED(off, size / sizeof(__u32)))

		return 0;

	if (KVM_REG_SIZE(reg->id) != size ||

	    !IS_ALIGNED(off, size / sizeof(__u32)))

		return -EINVAL;



	/*

	 * The KVM_REG_ARM64_SVE regs must be used instead of

	 * KVM_REG_ARM_CORE for accessing the FPSIMD V-registers on

	 * SVE-enabled vcpus:

	 */

	if (vcpu_has_sve(vcpu) && core_reg_offset_is_vreg(off))

		return -EINVAL;



	return 0;

}



static int get_core_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
@@ -117,7 +132,7 @@ static int get_core_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg) 
	    (off + (KVM_REG_SIZE(reg->id) / sizeof(__u32))) >= nr_regs)

		return -ENOENT;



	if (validate_core_offset(reg))

	if (validate_core_offset(vcpu, reg))

		return -EINVAL;



	if (copy_to_user(uaddr, ((u32 *)regs) + off, KVM_REG_SIZE(reg->id)))
@@ -142,7 +157,7 @@ static int set_core_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg) 
	    (off + (KVM_REG_SIZE(reg->id) / sizeof(__u32))) >= nr_regs)

		return -ENOENT;



	if (validate_core_offset(reg))

	if (validate_core_offset(vcpu, reg))

		return -EINVAL;



	if (KVM_REG_SIZE(reg->id) > sizeof(tmp))
@@ -195,13 +210,22 @@ int kvm_arch_vcpu_ioctl_set_regs(struct kvm_vcpu *vcpu, struct kvm_regs *regs) 
	return -EINVAL;

}



static int kvm_arm_copy_core_reg_indices(u64 __user *uindices)

static int copy_core_reg_indices(const struct kvm_vcpu *vcpu,

				 u64 __user *uindices)

{

	unsigned int i;

	int n = 0;

	const u64 core_reg = KVM_REG_ARM64 | KVM_REG_SIZE_U64 | KVM_REG_ARM_CORE;



	for (i = 0; i < sizeof(struct kvm_regs) / sizeof(__u32); i++) {

		/*

		 * The KVM_REG_ARM64_SVE regs must be used instead of

		 * KVM_REG_ARM_CORE for accessing the FPSIMD V-registers on

		 * SVE-enabled vcpus:

		 */

		if (vcpu_has_sve(vcpu) && core_reg_offset_is_vreg(i))

			continue;



		if (uindices) {

			if (put_user(core_reg | i, uindices))

				return -EFAULT;
@@ -214,9 +238,9 @@ static int kvm_arm_copy_core_reg_indices(u64 __user *uindices) 
	return n;

}



static unsigned long num_core_regs(void)

static unsigned long num_core_regs(const struct kvm_vcpu *vcpu)

{

	return kvm_arm_copy_core_reg_indices(NULL);

	return copy_core_reg_indices(vcpu, NULL);

}



/**
@@ -281,7 +305,7 @@ unsigned long kvm_arm_num_regs(struct kvm_vcpu *vcpu) 
{

	unsigned long res = 0;



	res += num_core_regs();

	res += num_core_regs(vcpu);

	res += kvm_arm_num_sys_reg_descs(vcpu);

	res += kvm_arm_get_fw_num_regs(vcpu);

	res += NUM_TIMER_REGS;
@@ -298,7 +322,7 @@ int kvm_arm_copy_reg_indices(struct kvm_vcpu *vcpu, u64 __user *uindices) 
{

	int ret;



	ret = kvm_arm_copy_core_reg_indices(uindices);

	ret = copy_core_reg_indices(vcpu, uindices);

	if (ret)

		return ret;

	uindices += ret;