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@xxxxxxx>
---
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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