From: Claudio Imbrenda <imbrenda@linux.ibm.com>
Date: Fri, 31 Jan 2020 15:00:39 -0500
Subject: KVM: s390/mm: handle guest unpin events
Git-commit: 5322781008a9dce894146ef71a09f1770062389a
Patch-mainline: v5.7-rc1
References: jsc#SLE-7512 bsc#1165545

The current code tries to first pin shared pages, if that fails (e.g.
because the page is not shared) it will export them. For shared pages
this means that we get a new intercept telling us that the guest is
unsharing that page. We will unpin the page at that point in time,
following the same rules as for making a page secure (i.e. waiting for
writeback, no elevated page references, etc.)

Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>

Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
[borntraeger@de.ibm.com: patch merging, splitting, fixing]
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 arch/s390/kvm/intercept.c |   29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

--- a/arch/s390/kvm/intercept.c
+++ b/arch/s390/kvm/intercept.c
@@ -16,6 +16,7 @@
 #include <asm/asm-offsets.h>
 #include <asm/irq.h>
 #include <asm/sysinfo.h>
+#include <asm/uv.h>
 
 #include "kvm-s390.h"
 #include "gaccess.h"
@@ -484,12 +485,40 @@ static int handle_pv_sclp(struct kvm_vcp
 	return 0;
 }
 
+static int handle_pv_uvc(struct kvm_vcpu *vcpu)
+{
+	struct uv_cb_share *guest_uvcb = (void *)vcpu->arch.sie_block->sidad;
+	struct uv_cb_cts uvcb = {
+		.header.cmd	= UVC_CMD_UNPIN_PAGE_SHARED,
+		.header.len	= sizeof(uvcb),
+		.guest_handle	= kvm_s390_pv_get_handle(vcpu->kvm),
+		.gaddr		= guest_uvcb->paddr,
+	};
+	int rc;
+
+	if (guest_uvcb->header.cmd != UVC_CMD_REMOVE_SHARED_ACCESS) {
+		WARN_ONCE(1, "Unexpected notification intercept for UVC 0x%x\n",
+			  guest_uvcb->header.cmd);
+		return 0;
+	}
+	rc = gmap_make_secure(vcpu->arch.gmap, uvcb.gaddr, &uvcb);
+	/*
+	 * If the unpin did not succeed, the guest will exit again for the UVC
+	 * and we will retry the unpin.
+	 */
+	if (rc == -EINVAL)
+		return 0;
+	return rc;
+}
+
 static int handle_pv_notification(struct kvm_vcpu *vcpu)
 {
 	if (vcpu->arch.sie_block->ipa == 0xb210)
 		return handle_pv_spx(vcpu);
 	if (vcpu->arch.sie_block->ipa == 0xb220)
 		return handle_pv_sclp(vcpu);
+	if (vcpu->arch.sie_block->ipa == 0xb9a4)
+		return handle_pv_uvc(vcpu);
 
 	return handle_instruction(vcpu);
 }