[PATCH v2 01/47] KVM: arm64: Allocate per-cpu memory for the host fpsimd state in pKVM

[Fuad Tabba <tabba@google.com>]

Allocate a per-cpu fpsimd_state to store the host's state when in
protected mode. Since the host_fpsimd_state pointer has been
excluded from kvm_vcpu_arch, no memory has been allocated to
store it in protected mode, and its value hasn't been set.

Fixes: 51e09b5572d6 ("KVM: arm64: Exclude host_fpsimd_state pointer from kvm_vcpu_arch")
Signed-off-by: Fuad Tabba <tabba@google.com>
---
 arch/arm64/kvm/hyp/include/nvhe/pkvm.h |  1 +
 arch/arm64/kvm/hyp/nvhe/pkvm.c         | 18 ++++++++++++++++++
 arch/arm64/kvm/hyp/nvhe/setup.c        |  1 +
 3 files changed, 20 insertions(+)

diff --git a/arch/arm64/kvm/hyp/include/nvhe/pkvm.h b/arch/arm64/kvm/hyp/include/nvhe/pkvm.h
index 82b3d62538a6..20c3f6e13b99 100644
--- a/arch/arm64/kvm/hyp/include/nvhe/pkvm.h
+++ b/arch/arm64/kvm/hyp/include/nvhe/pkvm.h
@@ -54,6 +54,7 @@ pkvm_hyp_vcpu_to_hyp_vm(struct pkvm_hyp_vcpu *hyp_vcpu)
 }
 
 void pkvm_hyp_vm_table_init(void *tbl);
+void pkvm_host_fpsimd_state_init(void);
 
 int __pkvm_init_vm(struct kvm *host_kvm, unsigned long vm_hva,
 		   unsigned long pgd_hva);
diff --git a/arch/arm64/kvm/hyp/nvhe/pkvm.c b/arch/arm64/kvm/hyp/nvhe/pkvm.c
index 26dd9a20ad6e..16ccb69e6479 100644
--- a/arch/arm64/kvm/hyp/nvhe/pkvm.c
+++ b/arch/arm64/kvm/hyp/nvhe/pkvm.c
@@ -18,6 +18,14 @@ unsigned long __icache_flags;
 /* Used by kvm_get_vttbr(). */
 unsigned int kvm_arm_vmid_bits;
 
+/*
+ * Host FPSIMD state. Written to when the guest accesses its own FPSIMD state,
+ * and read when the guest state is live and we need to switch back to the host.
+ *
+ * Only valid when guest_owns_fp_regs() is true.
+ */
+DEFINE_PER_CPU(struct user_fpsimd_state, host_fpsimd_state);
+
 /*
  * Set trap register values based on features in ID_AA64PFR0.
  */
@@ -247,6 +255,16 @@ void pkvm_hyp_vm_table_init(void *tbl)
 	vm_table = tbl;
 }
 
+void pkvm_host_fpsimd_state_init(void)
+{
+	unsigned long i;
+
+	for (i = 0; i < hyp_nr_cpus; i++) {
+		per_cpu_ptr(&kvm_host_data, i)->fpsimd_state =
+			per_cpu_ptr(&host_fpsimd_state, i);
+	}
+}
+
 /*
  * Return the hyp vm structure corresponding to the handle.
  */
diff --git a/arch/arm64/kvm/hyp/nvhe/setup.c b/arch/arm64/kvm/hyp/nvhe/setup.c
index ae00dfa80801..859f22f754d3 100644
--- a/arch/arm64/kvm/hyp/nvhe/setup.c
+++ b/arch/arm64/kvm/hyp/nvhe/setup.c
@@ -300,6 +300,7 @@ void __noreturn __pkvm_init_finalise(void)
 		goto out;
 
 	pkvm_hyp_vm_table_init(vm_table_base);
+	pkvm_host_fpsimd_state_init();
 out:
 	/*
 	 * We tail-called to here from handle___pkvm_init() and will not return,
-- 
2.44.0.683.g7961c838ac-goog