[RFC PATCH v3 15/24] KVM: arm64: Reject ioctl access to FPSIMD V-regs on SVE vcpus
From: Dave Martin <Dave.Martin@arm.com>
Date: 2018-12-11 23:33:38
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> --- Changes since RFC v2: * New patch The initial code was split from "KVM: arm64/sve: Add SVE support to register access ioctl interface". However, some additional refactoring makes this change quite noisy: for ease of review, I decided it was best to keep the two parts of the change separate. * Move core_reg_offset_is_vreg() before validate_core_reg_id() (which now makes use of it). * Move rejection of KVM_REG_ARM_CORE view of the FPSIMD V-regs on SVE-enabled vcpus into validate_core_reg_id(), so that it can be applied everywhere appropriate instead of being open-coded. This requires vcpu to be pushed down into a few code paths (This is the noise alluded to above). --- arch/arm64/kvm/guest.c | 39 +++++++++++++++++++++++++++------------ 1 file changed, 27 insertions(+), 12 deletions(-)
diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
index 0bf0ed3..e1ea73e 100644
--- a/arch/arm64/kvm/guest.c
+++ b/arch/arm64/kvm/guest.c@@ -83,7 +83,13 @@ static int core_reg_size_from_offset(u64 off) return -EINVAL; } -static int validate_core_reg_id(u64 id) +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 int validate_core_reg_id(const struct kvm_vcpu *vcpu, u64 id) { u64 off = core_reg_offset_from_id(id); int size = core_reg_size_from_offset(off);
@@ -91,10 +97,18 @@ static int validate_core_reg_id(u64 id) if (size < 0) return size; - if (KVM_REG_SIZE(id) == size && IS_ALIGNED(off, size / sizeof(__u32))) - return 0; + if (KVM_REG_SIZE(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)
@@ -116,7 +130,7 @@ 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_reg_id(reg->id)) + if (validate_core_reg_id(vcpu, reg->id)) return -EINVAL; if (copy_to_user(uaddr, ((u32 *)regs) + off, KVM_REG_SIZE(reg->id)))
@@ -141,7 +155,7 @@ 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_reg_id(reg->id)) + if (validate_core_reg_id(vcpu, reg->id)) return -EINVAL; if (KVM_REG_SIZE(reg->id) > sizeof(tmp))
@@ -194,7 +208,8 @@ int kvm_arch_vcpu_ioctl_set_regs(struct kvm_vcpu *vcpu, struct kvm_regs *regs) return -EINVAL; } -static int copy_core_reg_indices(u64 __user **uind) +static int copy_core_reg_indices(const struct kvm_vcpu *vcpu, + u64 __user **uind) { unsigned int i; int total = 0;
@@ -228,7 +243,7 @@ static int copy_core_reg_indices(u64 __user **uind) break; } - if (validate_core_reg_id(id)) + if (validate_core_reg_id(vcpu, id)) continue; if (uind) {
@@ -243,9 +258,9 @@ static int copy_core_reg_indices(u64 __user **uind) return total; } -static unsigned long num_core_regs(void) +static unsigned long num_core_regs(const struct kvm_vcpu *vcpu) { - return copy_core_reg_indices(NULL); + return copy_core_reg_indices(vcpu, NULL); } /**
@@ -310,7 +325,7 @@ 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;
@@ -327,7 +342,7 @@ int kvm_arm_copy_reg_indices(struct kvm_vcpu *vcpu, u64 __user *uindices) { int ret; - ret = copy_core_reg_indices(&uindices); + ret = copy_core_reg_indices(vcpu, &uindices); if (ret < 0) return ret;
--
2.1.4
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