[PATCH v6 17/27] KVM: arm64: Reject ioctl access to FPSIMD V-regs on SVE vcpus
From: Dave Martin <Dave.Martin@arm.com>
Date: 2019-03-19 17:57:41
Also in:
kvmarm
Subsystem:
arm64 port (aarch64 architecture), kernel virtual machine for arm64 (kvm/arm64), the rest · Maintainers:
Catalin Marinas, Will Deacon, Marc Zyngier, Oliver Upton, Linus Torvalds
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: Dave Martin <Dave.Martin@arm.com> --- (Julien Thierry's Reviewed-by dropped due to non-trivial refactoring) Changes since v5: * Refactored to cope with the removal of core_reg_size_from_offset() (which was added by another series which will now be handled independently). This leaves some duplication in that we still filter the V-regs out in two places, but this no worse than other existing code in guest.c. I plan to tidy this up independently later on. --- arch/arm64/kvm/guest.c | 48 ++++++++++++++++++++++++++++++++++++------------ 1 file changed, 36 insertions(+), 12 deletions(-)
diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
index a391a61..756d0d6 100644
--- a/arch/arm64/kvm/guest.c
+++ b/arch/arm64/kvm/guest.c@@ -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; - 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;
--
2.1.4
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