KVM: s390: vsie: stop using page->index

Let's stop using page->index, and instead use a field inside "struct
vsie_page" to hold that value. We have plenty of space left in there.

This is one part of stopping using "struct page" when working with vsie
pages. We place the "page_to_virt(page)" strategically, so the next
cleanups requires less churn.

Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: Christoph Schlameuss <schlameuss@linux.ibm.com>
Tested-by: Christoph Schlameuss <schlameuss@linux.ibm.com>
Message-ID: <20250107154344.1003072-3-david@redhat.com>
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>

diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
index 513e608567ccc4bde25cc35b704bd80e8d76a5a5..3874a1b49dd54cb906910ae56c33ab6d32637274 100644 (file)
--- a/arch/s390/kvm/vsie.c
+++ b/arch/s390/kvm/vsie.c
@@ -46,7 +46,13 @@ struct vsie_page {
        gpa_t gvrd_gpa;                         /* 0x0240 */
        gpa_t riccbd_gpa;                       /* 0x0248 */
        gpa_t sdnx_gpa;                         /* 0x0250 */
-       __u8 reserved[0x0700 - 0x0258];         /* 0x0258 */
+       /*
+        * guest address of the original SCB. Remains set for free vsie
+        * pages, so we can properly look them up in our addr_to_page
+        * radix tree.
+        */
+       gpa_t scb_gpa;                          /* 0x0258 */
+       __u8 reserved[0x0700 - 0x0260];         /* 0x0260 */
        struct kvm_s390_crypto_cb crycb;        /* 0x0700 */
        __u8 fac[S390_ARCH_FAC_LIST_SIZE_BYTE]; /* 0x0800 */
 };
@@ -1362,9 +1368,10 @@ static struct vsie_page *get_vsie_page(struct kvm *kvm, unsigned long addr)
        page = radix_tree_lookup(&kvm->arch.vsie.addr_to_page, addr >> 9);
        rcu_read_unlock();
        if (page) {
+               vsie_page = page_to_virt(page);
                if (page_ref_inc_return(page) == 2) {
-                       if (page->index == addr)
-                               return page_to_virt(page);
+                       if (vsie_page->scb_gpa == addr)
+                               return vsie_page;
                        /*
                         * We raced with someone reusing + putting this vsie
                         * page before we grabbed it.
@@ -1386,6 +1393,7 @@ static struct vsie_page *get_vsie_page(struct kvm *kvm, unsigned long addr)
                        mutex_unlock(&kvm->arch.vsie.mutex);
                        return ERR_PTR(-ENOMEM);
                }
+               vsie_page = page_to_virt(page);
                page_ref_inc(page);
                kvm->arch.vsie.pages[kvm->arch.vsie.page_count] = page;
                kvm->arch.vsie.page_count++;
@@ -1393,18 +1401,19 @@ static struct vsie_page *get_vsie_page(struct kvm *kvm, unsigned long addr)
                /* reuse an existing entry that belongs to nobody */
                while (true) {
                        page = kvm->arch.vsie.pages[kvm->arch.vsie.next];
+                       vsie_page = page_to_virt(page);
                        if (page_ref_inc_return(page) == 2)
                                break;
                        page_ref_dec(page);
                        kvm->arch.vsie.next++;
                        kvm->arch.vsie.next %= nr_vcpus;
                }
-               if (page->index != ULONG_MAX)
+               if (vsie_page->scb_gpa != ULONG_MAX)
                        radix_tree_delete(&kvm->arch.vsie.addr_to_page,
-                                         page->index >> 9);
+                                         vsie_page->scb_gpa >> 9);
        }
        /* Mark it as invalid until it resides in the tree. */
-       page->index = ULONG_MAX;
+       vsie_page->scb_gpa = ULONG_MAX;
 
        /* Double use of the same address or allocation failure. */
        if (radix_tree_insert(&kvm->arch.vsie.addr_to_page, addr >> 9, page)) {
@@ -1412,10 +1421,9 @@ static struct vsie_page *get_vsie_page(struct kvm *kvm, unsigned long addr)
                mutex_unlock(&kvm->arch.vsie.mutex);
                return NULL;
        }
-       page->index = addr;
+       vsie_page->scb_gpa = addr;
        mutex_unlock(&kvm->arch.vsie.mutex);
 
-       vsie_page = page_to_virt(page);
        memset(&vsie_page->scb_s, 0, sizeof(struct kvm_s390_sie_block));
        release_gmap_shadow(vsie_page);
        vsie_page->fault_addr = 0;
@@ -1507,9 +1515,9 @@ void kvm_s390_vsie_destroy(struct kvm *kvm)
                vsie_page = page_to_virt(page);
                release_gmap_shadow(vsie_page);
                /* free the radix tree entry */
-               if (page->index != ULONG_MAX)
+               if (vsie_page->scb_gpa != ULONG_MAX)
                        radix_tree_delete(&kvm->arch.vsie.addr_to_page,
-                                         page->index >> 9);
+                                         vsie_page->scb_gpa >> 9);
                __free_page(page);
        }
        kvm->arch.vsie.page_count = 0;