[PATCH 4/4] KVM: arm64: Allow protected VMs to use SVE

[Fuad Tabba <fuad.tabba@linux.dev>]

Now that EL2 owns a protected vCPU's SVE state and advertises
ID_AA64ZFR0_EL1, allow KVM_CAP_ARM_SVE for a protected VM, which lets
KVM_ARM_VCPU_INIT take KVM_ARM_VCPU_SVE.

A protected guest's SVE access trap injects an UNDEF. An SVE
instruction takes the SVE trap rather than the FP one, so a guest whose
first vector instruction is an SVE one would get an UNDEF instead of
the lazy FP switch. Handle the SVE trap as the FP trap is:
kvm_handle_pvm_fpsimd() switches the state for a vCPU with SVE and
still injects the UNDEF for one without.

Update the documentation to match.

Signed-off-by: Fuad Tabba <fuad.tabba@linux.dev>
---
 Documentation/virt/kvm/arm/pkvm.rst | 6 +++---
 arch/arm64/include/asm/kvm_pkvm.h   | 1 +
 arch/arm64/kvm/hyp/nvhe/switch.c    | 1 +
 arch/arm64/kvm/hyp/nvhe/sys_regs.c  | 2 --
 4 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/Documentation/virt/kvm/arm/pkvm.rst b/Documentation/virt/kvm/arm/pkvm.rst
index b75bb8ad6f26d..163aa01ac5067 100644
--- a/Documentation/virt/kvm/arm/pkvm.rst
+++ b/Documentation/virt/kvm/arm/pkvm.rst
@@ -134,9 +134,9 @@ A protected VM boots from a single primary vCPU. Before the first
 * Set the primary vCPU's boot state with ``KVM_SET_ONE_REG``: the kernel
   entry address in ``PC`` and the DTB pointer in ``x0``.
 
-``PC`` and ``x0`` are the only registers EL2 takes from the host. Other
-pre-run writes are accepted, but the guest starts from the state the
-hypervisor resets it to.
+``PC``, ``x0`` and the SVE vector lengths (``KVM_REG_ARM64_SVE_VLS``) are
+the only registers EL2 takes from the host. Other pre-run writes are
+accepted, but the guest starts from the state the hypervisor resets it to.
 
 Secondary vCPUs are started by the guest itself through PSCI ``CPU_ON``
 (see `Power state`_), which supplies their entry point and context ID.
diff --git a/arch/arm64/include/asm/kvm_pkvm.h b/arch/arm64/include/asm/kvm_pkvm.h
index fd042d2b54624..5f1b3308b42e1 100644
--- a/arch/arm64/include/asm/kvm_pkvm.h
+++ b/arch/arm64/include/asm/kvm_pkvm.h
@@ -40,6 +40,7 @@ static inline bool kvm_pkvm_ext_allowed(struct kvm *kvm, long ext)
 	case KVM_CAP_MAX_VCPU_ID:
 	case KVM_CAP_MSI_DEVID:
 	case KVM_CAP_ARM_VM_IPA_SIZE:
+	case KVM_CAP_ARM_SVE:
 	case KVM_CAP_ARM_PTRAUTH_ADDRESS:
 	case KVM_CAP_ARM_PTRAUTH_GENERIC:
 	case KVM_CAP_ONE_REG:
diff --git a/arch/arm64/kvm/hyp/nvhe/switch.c b/arch/arm64/kvm/hyp/nvhe/switch.c
index 89fb9dd351ad5..0626f4203ba6d 100644
--- a/arch/arm64/kvm/hyp/nvhe/switch.c
+++ b/arch/arm64/kvm/hyp/nvhe/switch.c
@@ -230,6 +230,7 @@ static const exit_handler_fn pvm_exit_handlers[] = {
 	[ESR_ELx_EC_WFx]		= kvm_handle_pvm_wfx,
 	[ESR_ELx_EC_HVC64]		= kvm_handle_pvm_hvc64,
 	[ESR_ELx_EC_SYS64]		= kvm_handle_pvm_sys64,
+	[ESR_ELx_EC_SVE]		= kvm_handle_pvm_fpsimd,
 	[ESR_ELx_EC_FP_ASIMD]		= kvm_handle_pvm_fpsimd,
 	[ESR_ELx_EC_IABT_LOW]		= kvm_hyp_handle_iabt_low,
 	[ESR_ELx_EC_DABT_LOW]		= kvm_hyp_handle_dabt_low,
diff --git a/arch/arm64/kvm/hyp/nvhe/sys_regs.c b/arch/arm64/kvm/hyp/nvhe/sys_regs.c
index e6bbc897cd7b1..0ddddf957f5ab 100644
--- a/arch/arm64/kvm/hyp/nvhe/sys_regs.c
+++ b/arch/arm64/kvm/hyp/nvhe/sys_regs.c
@@ -502,8 +502,6 @@ static const struct sys_reg_desc pvm_sys_reg_descs[] = {
 	ID_UNALLOCATED(7,6),
 	ID_UNALLOCATED(7,7),
 
-	/* Scalable Vector Registers are restricted. */
-
 	HOST_HANDLED(SYS_ICC_PMR_EL1),
 
 	RAZ_WI(SYS_ERRIDR_EL1),
-- 
2.47.3