[PATCH 2/3] KVM: PPC: Book3S HV: Implement virtual mode H_PAGE_INIT handler

[Suraj Jitindar Singh <sjitindarsingh@xxxxxxxxx>]

Implement a virtual mode handler for the H_CALL H_PAGE_INIT which can be
used to zero or copy a guest page. The page is defined to be 4k and must
be 4k aligned.

The in-kernel handler halves the time to handle this H_CALL compared to
handling it in userspace for a radix guest.

Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@xxxxxxxxx>
---
 arch/powerpc/kvm/book3s_hv.c | 39 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 7179ea783f4f..fa29cc4900c2 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -883,6 +883,39 @@ static int kvmppc_copy_guest(struct kvm *kvm, gpa_t to, gpa_t from,
 	return 0;
 }
 
+static int kvmppc_h_page_init(struct kvm_vcpu *vcpu, unsigned long flags,
+			      unsigned long dest, unsigned long src)
+{
+	int ret = H_FUNCTION;
+	u64 pg_sz = 1UL << 12;	/* 4K page size */
+	u64 pg_mask = pg_sz - 1;
+
+	/* Check for invalid flags (H_PAGE_SET_LOANED covers all CMO flags) */
+	if (flags & ~(H_ICACHE_INVALIDATE | H_ICACHE_SYNCHRONIZE |
+		      H_ZERO_PAGE | H_COPY_PAGE | H_PAGE_SET_LOANED))
+		return H_PARAMETER;
+
+	/* dest (and src if copy_page flag set) must be page aligned */
+	if ((dest & pg_mask) || ((flags & H_COPY_PAGE) && (src & pg_mask)))
+		return H_PARAMETER;
+
+	/* zero and/or copy the page as determined by the flags */
+	if (flags & H_ZERO_PAGE) {
+		ret = kvm_clear_guest(vcpu->kvm, dest, pg_sz);
+		if (ret < 0)
+			return H_PARAMETER;
+	}
+	if (flags & H_COPY_PAGE) {
+		ret = kvmppc_copy_guest(vcpu->kvm, dest, src, pg_sz);
+		if (ret < 0)
+			return H_PARAMETER;
+	}
+
+	/* We can ignore the remaining flags */
+
+	return H_SUCCESS;
+}
+
 static int kvm_arch_vcpu_yield_to(struct kvm_vcpu *target)
 {
 	struct kvmppc_vcore *vcore = target->arch.vcore;
@@ -1083,6 +1116,11 @@ int kvmppc_pseries_do_hcall(struct kvm_vcpu *vcpu)
 		if (nesting_enabled(vcpu->kvm))
 			ret = kvmhv_copy_tofrom_guest_nested(vcpu);
 		break;
+	case H_PAGE_INIT:
+		ret = kvmppc_h_page_init(vcpu, kvmppc_get_gpr(vcpu, 4),
+					 kvmppc_get_gpr(vcpu, 5),
+					 kvmppc_get_gpr(vcpu, 6));
+		break;
 	default:
 		return RESUME_HOST;
 	}
@@ -1127,6 +1165,7 @@ static int kvmppc_hcall_impl_hv(unsigned long cmd)
 	case H_IPOLL:
 	case H_XIRR_X:
 #endif
+	case H_PAGE_INIT:
 		return 1;
 	}
 
-- 
2.13.6