[RFC,kvmtool,v1,31/32] pkvm: Handle (un)share hypercalls coming from the guest

Commit Message

Fuad Tabba Dec. 2, 2022, 5:44 p.m. UTC

(Un)map guest memory if it's sharing status changes.

Signed-off-by: Fuad Tabba <[e-mail]>
---
 arm/aarch64/include/asm/kvm.h |  7 +++++
 arm/kvm-cpu.c                 | 58 ++++++++++++++++++++++++++++++++---
 2 files changed, 60 insertions(+), 5 deletions(-)

Patch

diff --git a/arm/aarch64/include/asm/kvm.h b/arm/aarch64/include/asm/kvm.h
index 316917b..662c178 100644
--- a/arm/aarch64/include/asm/kvm.h
+++ b/arm/aarch64/include/asm/kvm.h
@@ -467,6 +467,13 @@  enum {
 /* run->fail_entry.hardware_entry_failure_reason codes. */
 #define KVM_EXIT_FAIL_ENTRY_CPU_UNSUPPORTED	(1ULL << 0)
 
+#define ARM_SMCCC_KVM_FUNC_MEM_SHARE		3
+#define ARM_SMCCC_KVM_FUNC_MEM_UNSHARE		4
+
+#define KVM_EXIT_HYPERCALL_VALID_MASK	((1ULL << ARM_SMCCC_KVM_FUNC_MEM_SHARE) |	\
+					 (1ULL << ARM_SMCCC_KVM_FUNC_MEM_UNSHARE))
+
+
 #endif
 
 #endif /* __ARM_KVM_H__ */
diff --git a/arm/kvm-cpu.c b/arm/kvm-cpu.c
index cb5a92a..fcefec8 100644
--- a/arm/kvm-cpu.c
+++ b/arm/kvm-cpu.c
@@ -144,16 +144,64 @@  void kvm_cpu__delete(struct kvm_cpu *vcpu)
 	free(vcpu);
 }
 
-bool kvm_cpu__handle_exit(struct kvm_cpu *vcpu)
+static bool handle_mem_share(struct kvm_cpu *vcpu)
 {
-	switch (vcpu->kvm_run->exit_reason) {
-	case KVM_EXIT_HYPERCALL:
-		pr_warning("Unhandled exit hypercall: 0x%llx, 0x%llx, 0x%llx, 0x%llx",
+	u64 gpa = vcpu->kvm_run->hypercall.args[0];
+
+	if (!vcpu->kvm->cfg.pkvm) {
+		pr_warning("%s: non-protected guest memshare request for gpa 0x%llx",
+			   __func__, gpa);
+		return true;
+	}
+
+	map_guest_range(vcpu->kvm, gpa, PAGE_SIZE);
+
+	return true;
+}
+
+static bool handle_mem_unshare(struct kvm_cpu *vcpu)
+{
+	u64 gpa = vcpu->kvm_run->hypercall.args[0];
+
+	if (!vcpu->kvm->cfg.pkvm) {
+		pr_warning("%s: non-protected guest memunshare request for gpa 0x%llx",
+			   __func__, gpa);
+		return true;
+	}
+
+	unmap_guest_range(vcpu->kvm, gpa, PAGE_SIZE);
+
+	return true;
+}
+
+static bool handle_hypercall(struct kvm_cpu *vcpu)
+{
+	u64 call_nr = vcpu->kvm_run->hypercall.nr;
+
+	switch (call_nr)
+	{
+	case ARM_SMCCC_KVM_FUNC_MEM_SHARE:
+		return handle_mem_share(vcpu);
+	case ARM_SMCCC_KVM_FUNC_MEM_UNSHARE:
+		return handle_mem_unshare(vcpu);
+	default:
+		pr_warning("%s: Unhandled exit hypercall: 0x%llx, 0x%llx, 0x%llx, 0x%llx",
+			   __func__,
 			   vcpu->kvm_run->hypercall.nr,
 			   vcpu->kvm_run->hypercall.ret,
 			   vcpu->kvm_run->hypercall.args[0],
 			   vcpu->kvm_run->hypercall.args[1]);
-		return true;
+		break;
+	}
+
+	return true;
+}
+
+bool kvm_cpu__handle_exit(struct kvm_cpu *vcpu)
+{
+	switch (vcpu->kvm_run->exit_reason) {
+	case KVM_EXIT_HYPERCALL:
+		return handle_hypercall(vcpu);
 	}
 
 	return false;