[GIT PULL v2 02/20] KVM: s390: vsie: stop using page->index

Claudio Imbrenda
2025-01-31T11:25:24Z

From: David Hildenbrand <david@redhat.com>

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>
---
arch/s390/kvm/vsie.c | 28 ++++++++++++++++++----------
1 file changed, 18 insertions(+), 10 deletions(-)

diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
index 513e608567cc..3874a1b49dd5 100644
--- 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;
--
2.48.1