Patch "KVM: s390: gaccess: Cleanup access to guest pages" has been added to the 4.19-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    KVM: s390: gaccess: Cleanup access to guest pages

to the 4.19-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     kvm-s390-gaccess-cleanup-access-to-guest-pages.patch
and it can be found in the queue-4.19 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 97606368a1835744cfafc3eb3c875ff1afda1e1c
Author: Janis Schoetterl-Glausch <scgl@xxxxxxxxxxxxx>
Date:   Fri Nov 26 17:45:49 2021 +0100

    KVM: s390: gaccess: Cleanup access to guest pages
    
    [ Upstream commit bad13799e0305deb258372b7298a86be4c78aaba ]
    
    Introduce a helper function for guest frame access.
    
    Signed-off-by: Janis Schoetterl-Glausch <scgl@xxxxxxxxxxxxx>
    Reviewed-by: Janosch Frank <frankja@xxxxxxxxxxxxx>
    Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
    Reviewed-by: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx>
    Message-Id: <20211126164549.7046-4-scgl@xxxxxxxxxxxxx>
    Signed-off-by: Janosch Frank <frankja@xxxxxxxxxxxxx>
    Stable-dep-of: e8061f06185b ("KVM: s390: gaccess: Check if guest address is in memslot")
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/arch/s390/kvm/gaccess.c b/arch/s390/kvm/gaccess.c
index d4fe5db5984dd..6ba82fe0776f8 100644
--- a/arch/s390/kvm/gaccess.c
+++ b/arch/s390/kvm/gaccess.c
@@ -866,6 +866,20 @@ static int guest_range_to_gpas(struct kvm_vcpu *vcpu, unsigned long ga, u8 ar,
 	return 0;
 }
 
+static int access_guest_page(struct kvm *kvm, enum gacc_mode mode, gpa_t gpa,
+			     void *data, unsigned int len)
+{
+	const unsigned int offset = offset_in_page(gpa);
+	const gfn_t gfn = gpa_to_gfn(gpa);
+	int rc;
+
+	if (mode == GACC_STORE)
+		rc = kvm_write_guest_page(kvm, gfn, data, offset, len);
+	else
+		rc = kvm_read_guest_page(kvm, gfn, data, offset, len);
+	return rc;
+}
+
 int access_guest(struct kvm_vcpu *vcpu, unsigned long ga, u8 ar, void *data,
 		 unsigned long len, enum gacc_mode mode)
 {
@@ -896,10 +910,7 @@ int access_guest(struct kvm_vcpu *vcpu, unsigned long ga, u8 ar, void *data,
 	rc = guest_range_to_gpas(vcpu, ga, ar, gpas, len, asce, mode);
 	for (idx = 0; idx < nr_pages && !rc; idx++) {
 		fragment_len = min(PAGE_SIZE - offset_in_page(gpas[idx]), len);
-		if (mode == GACC_STORE)
-			rc = kvm_write_guest(vcpu->kvm, gpas[idx], data, fragment_len);
-		else
-			rc = kvm_read_guest(vcpu->kvm, gpas[idx], data, fragment_len);
+		rc = access_guest_page(vcpu->kvm, mode, gpas[idx], data, fragment_len);
 		len -= fragment_len;
 		data += fragment_len;
 	}
@@ -920,10 +931,7 @@ int access_guest_real(struct kvm_vcpu *vcpu, unsigned long gra,
 	while (len && !rc) {
 		gpa = kvm_s390_real_to_abs(vcpu, gra);
 		fragment_len = min(PAGE_SIZE - offset_in_page(gpa), len);
-		if (mode)
-			rc = write_guest_abs(vcpu, gpa, data, fragment_len);
-		else
-			rc = read_guest_abs(vcpu, gpa, data, fragment_len);
+		rc = access_guest_page(vcpu->kvm, mode, gpa, data, fragment_len);
 		len -= fragment_len;
 		gra += fragment_len;
 		data += fragment_len;