KVM: s390: Simplify and move pv code

JIRA: https://issues.redhat.com/browse/RHEL-113440

commit d6c8097
Author: Claudio Imbrenda <imbrenda@linux.ibm.com>
Date:   Wed May 28 11:55:02 2025 +0200

    KVM: s390: Simplify and move pv code

    All functions in kvm/gmap.c fit better in kvm/pv.c instead.
    Move and rename them appropriately, then delete the now empty
    kvm/gmap.c and kvm/gmap.h.

    Reviewed-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
    Reviewed-by: Steffen Eiden <seiden@linux.ibm.com>
    Reviewed-by: Christoph Schlameuss <schlameuss@linux.ibm.com>
    Acked-by: Janosch Frank <frankja@linux.ibm.com>
    Link: https://lore.kernel.org/r/20250528095502.226213-5-imbrenda@linux.ibm.com
    Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
    Message-ID: <20250528095502.226213-5-imbrenda@linux.ibm.com>

Signed-off-by: Thomas Huth <thuth@redhat.com>

Author: huth

arch/s390/kernel/uv.c

@@ -136,7 +136,7 @@ int uv_destroy_folio(struct folio *folio)
 {
 	int rc;
 
-	/* See gmap_make_secure(): large folios cannot be secure */
+	/* Large folios cannot be secure */
 	if (unlikely(folio_test_large(folio)))
 		return 0;
 
@@ -185,7 +185,7 @@ int uv_convert_from_secure_folio(struct folio *folio)
 {
 	int rc;
 
-	/* See gmap_make_secure(): large folios cannot be secure */
+	/* Large folios cannot be secure */
 	if (unlikely(folio_test_large(folio)))
 		return 0;
 
@@ -462,15 +462,15 @@ EXPORT_SYMBOL_GPL(make_hva_secure);
 
 /*
  * To be called with the folio locked or with an extra reference! This will
- * prevent gmap_make_secure from touching the folio concurrently. Having 2
- * parallel arch_make_folio_accessible is fine, as the UV calls will become a
- * no-op if the folio is already exported.
+ * prevent kvm_s390_pv_make_secure() from touching the folio concurrently.
+ * Having 2 parallel arch_make_folio_accessible is fine, as the UV calls will
+ * become a no-op if the folio is already exported.
  */
 int arch_make_folio_accessible(struct folio *folio)
 {
 	int rc = 0;
 
-	/* See gmap_make_secure(): large folios cannot be secure */
+	/* Large folios cannot be secure */
 	if (unlikely(folio_test_large(folio)))
 		return 0;
 

arch/s390/kvm/Makefile

@@ -8,7 +8,7 @@ include $(srctree)/virt/kvm/Makefile.kvm
 ccflags-y := -Ivirt/kvm -Iarch/s390/kvm
 
 kvm-y += kvm-s390.o intercept.o interrupt.o priv.o sigp.o
-kvm-y += diag.o gaccess.o guestdbg.o vsie.o pv.o gmap.o gmap-vsie.o
+kvm-y += diag.o gaccess.o guestdbg.o vsie.o pv.o gmap-vsie.o
 
 kvm-$(CONFIG_VFIO_PCI_ZDEV_KVM) += pci.o
 obj-$(CONFIG_KVM) += kvm.o

arch/s390/kvm/gaccess.c

@@ -16,9 +16,10 @@
 #include <asm/gmap.h>
 #include <asm/dat-bits.h>
 #include "kvm-s390.h"
-#include "gmap.h"
 #include "gaccess.h"
 
+#define GMAP_SHADOW_FAKE_TABLE 1ULL
+
 /*
  * vaddress union in order to easily decode a virtual address into its
  * region first index, region second index etc. parts.

arch/s390/kvm/gmap-vsie.c

@@ -22,7 +22,6 @@
 #include <asm/uv.h>
 
 #include "kvm-s390.h"
-#include "gmap.h"
 
 /**
  * gmap_find_shadow - find a specific asce in the list of shadow tables

arch/s390/kvm/gmap.c

@@ -16,13 +16,11 @@
 #include <asm/irq.h>
 #include <asm/sysinfo.h>
 #include <asm/uv.h>
-#include <asm/gmap.h>
 
 #include "kvm-s390.h"
 #include "gaccess.h"
 #include "trace.h"
 #include "trace-s390.h"
-#include "gmap.h"
 
 u8 kvm_s390_get_ilen(struct kvm_vcpu *vcpu)
 {
@@ -546,7 +544,7 @@ static int handle_pv_uvc(struct kvm_vcpu *vcpu)
 			  guest_uvcb->header.cmd);
 		return 0;
 	}
-	rc = gmap_make_secure(vcpu->arch.gmap, uvcb.gaddr, &uvcb);
+	rc = kvm_s390_pv_make_secure(vcpu->kvm, uvcb.gaddr, &uvcb);
 	/*
 	 * If the unpin did not succeed, the guest will exit again for the UVC
 	 * and we will retry the unpin.
@@ -654,10 +652,8 @@ int kvm_handle_sie_intercept(struct kvm_vcpu *vcpu)
 		break;
 	case ICPT_PV_PREF:
 		rc = 0;
-		gmap_convert_to_secure(vcpu->arch.gmap,
-				       kvm_s390_get_prefix(vcpu));
-		gmap_convert_to_secure(vcpu->arch.gmap,
-				       kvm_s390_get_prefix(vcpu) + PAGE_SIZE);
+		kvm_s390_pv_convert_to_secure(vcpu->kvm, kvm_s390_get_prefix(vcpu));
+		kvm_s390_pv_convert_to_secure(vcpu->kvm, kvm_s390_get_prefix(vcpu) + PAGE_SIZE);
 		break;
 	default:
 		return -EOPNOTSUPP;

arch/s390/kvm/gmap.h

@@ -51,7 +51,6 @@
 #include "kvm-s390.h"
 #include "gaccess.h"
 #include "pci.h"
-#include "gmap.h"
 
 #define CREATE_TRACE_POINTS
 #include "trace.h"
@@ -4974,7 +4973,7 @@ static int vcpu_post_run_handle_fault(struct kvm_vcpu *vcpu)
 		 * previous protected guest. The old pages need to be destroyed
 		 * so the new guest can use them.
 		 */
-		if (gmap_destroy_page(vcpu->arch.gmap, gaddr)) {
+		if (kvm_s390_pv_destroy_page(vcpu->kvm, gaddr)) {
 			/*
 			 * Either KVM messed up the secure guest mapping or the
 			 * same page is mapped into multiple secure guests.
@@ -4996,7 +4995,7 @@ static int vcpu_post_run_handle_fault(struct kvm_vcpu *vcpu)
 		 * guest has not been imported yet. Try to import the page into
 		 * the protected guest.
 		 */
-		rc = gmap_convert_to_secure(vcpu->arch.gmap, gaddr);
+		rc = kvm_s390_pv_convert_to_secure(vcpu->kvm, gaddr);
 		if (rc == -EINVAL)
 			send_sig(SIGSEGV, current, 0);
 		if (rc != -ENXIO)

arch/s390/kvm/intercept.c

@@ -308,6 +308,9 @@ int kvm_s390_pv_dump_stor_state(struct kvm *kvm, void __user *buff_user,
 				u64 *gaddr, u64 buff_user_len, u16 *rc, u16 *rrc);
 int kvm_s390_pv_dump_complete(struct kvm *kvm, void __user *buff_user,
 			      u16 *rc, u16 *rrc);
+int kvm_s390_pv_destroy_page(struct kvm *kvm, unsigned long gaddr);
+int kvm_s390_pv_convert_to_secure(struct kvm *kvm, unsigned long gaddr);
+int kvm_s390_pv_make_secure(struct kvm *kvm, unsigned long gaddr, void *uvcb);
 
 static inline u64 kvm_s390_pv_get_handle(struct kvm *kvm)
 {
@@ -319,6 +322,41 @@ static inline u64 kvm_s390_pv_cpu_get_handle(struct kvm_vcpu *vcpu)
 	return vcpu->arch.pv.handle;
 }
 
+/**
+ * __kvm_s390_pv_destroy_page() - Destroy a guest page.
+ * @page: the page to destroy
+ *
+ * An attempt will be made to destroy the given guest page. If the attempt
+ * fails, an attempt is made to export the page. If both attempts fail, an
+ * appropriate error is returned.
+ *
+ * Context: must be called holding the mm lock for gmap->mm
+ */
+static inline int __kvm_s390_pv_destroy_page(struct page *page)
+{
+	struct folio *folio = page_folio(page);
+	int rc;
+
+	/* Large folios cannot be secure. Small folio implies FW_LEVEL_PTE. */
+	if (folio_test_large(folio))
+		return -EFAULT;
+
+	rc = uv_destroy_folio(folio);
+	/*
+	 * Fault handlers can race; it is possible that two CPUs will fault
+	 * on the same secure page. One CPU can destroy the page, reboot,
+	 * re-enter secure mode and import it, while the second CPU was
+	 * stuck at the beginning of the handler. At some point the second
+	 * CPU will be able to progress, and it will not be able to destroy
+	 * the page. In that case we do not want to terminate the process,
+	 * we instead try to export the page.
+	 */
+	if (rc)
+		rc = uv_convert_from_secure_folio(folio);
+
+	return rc;
+}
+
 /* implemented in interrupt.c */
 int kvm_s390_handle_wait(struct kvm_vcpu *vcpu);
 void kvm_s390_vcpu_wakeup(struct kvm_vcpu *vcpu);
@@ -398,6 +436,10 @@ void kvm_s390_vsie_gmap_notifier(struct gmap *gmap, unsigned long start,
 				 unsigned long end);
 void kvm_s390_vsie_init(struct kvm *kvm);
 void kvm_s390_vsie_destroy(struct kvm *kvm);
+int gmap_shadow_valid(struct gmap *sg, unsigned long asce, int edat_level);
+
+/* implemented in gmap-vsie.c */
+struct gmap *gmap_shadow(struct gmap *parent, unsigned long asce, int edat_level);
 
 /* implemented in sigp.c */
 int kvm_s390_handle_sigp(struct kvm_vcpu *vcpu);