On Fri, Feb 22, 2019 at 09:05:16AM +0000, Julien Thierry wrote:

Hi Dave,

On 18/02/2019 19:52, Dave Martin wrote:

quoted

Now that all the pieces are in place, this patch offers a new flag
KVM_ARM_VCPU_SVE that userspace can pass to KVM_ARM_VCPU_INIT to
turn on SVE for the guest, on a per-vcpu basis.

As part of this, support for initialisation and reset of the SVE
vector length set and registers is added in the appropriate places.
Allocation SVE registers is deferred until kvm_arm_vcpu_finalize(),
by which time the size of the registers is known.

Setting the vector lengths supported by the vcpu is considered
configuration of the emulated hardware rather than runtime
configuration, so no support is offered for changing the vector
lengths of an existing vcpu across reset.

Signed-off-by: Dave Martin <Dave.Martin@arm.com>

---

Changes since v4:

 * Pull out vcpu_sve_state_size(), for use earlier in the series.

 * Remove unnecessary vcpu->arch.sve_vqs[], and clamp maximum guest
   vector length to 256 bytes for forwards compatibility.

   (See "KVM: arm64/sve: Add pseudo-register for the guest's vector
   lengths".)

 * Minor tidyups to make some checks less verbose.
---
 arch/arm64/include/asm/kvm_host.h |  2 +-
 arch/arm64/include/uapi/asm/kvm.h |  1 +
 arch/arm64/kvm/reset.c            | 70 ++++++++++++++++++++++++++++++++++++++-
 3 files changed, 71 insertions(+), 2 deletions(-)

[...]

quoted

diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c

[...]

quoted

 int kvm_arm_vcpu_finalize(struct kvm_vcpu *vcpu)
 {
 	if (likely(kvm_arm_vcpu_finalized(vcpu)))
 		return 0;
 
+	if (vcpu_has_sve(vcpu)) {
+		size_t size = vcpu_sve_state_size(vcpu);
+
+		if (!size)
+			return -EINVAL;
+
+		vcpu->arch.sve_state = kzalloc(size, GFP_KERNEL);

We should probably free this in kvm_arch_vcpu_free().

Hmmm, good spot!

Looks like I lost that during a previous rebase.

Cheers
---Dave

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