s390/mm/fault: Handle guest-related program interrupts in KVM

Any program interrupt that happens in the host during the execution of
a KVM guest will now short circuit the fault handler and return to KVM
immediately. Guest fault handling (including pfault) will happen
entirely inside KVM.

When sie64a() returns zero, current->thread.gmap_int_code will contain
the program interrupt number that caused the exit, or zero if the exit
was not caused by a host program interrupt.

KVM will now take care of handling all guest faults in vcpu_post_run().

Since gmap faults will not be visible by the rest of the kernel, remove
GMAP_FAULT, the linux fault handlers for secure execution faults, the
exception table entries for the sie instruction, the nop padding after
the sie instruction, and all other references to guest faults from the
s390 code.

Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Co-developed-by: Heiko Carstens <hca@linux.ibm.com>
Link: https://lore.kernel.org/r/20241022120601.167009-6-imbrenda@linux.ibm.com
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

1 files changed, 1 insertions, 98 deletions

diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
index a6cf33b0f339..e48910b0b816 100644
--- a/arch/s390/mm/fault.c
+++ b/arch/s390/mm/fault.c
@@ -49,7 +49,6 @@
 enum fault_type {
 	KERNEL_FAULT,
 	USER_FAULT,
-	GMAP_FAULT,
 };
 
 static DEFINE_STATIC_KEY_FALSE(have_store_indication);
@@ -72,10 +71,6 @@ static enum fault_type get_fault_type(struct pt_regs *regs)
 	if (likely(teid.as == PSW_BITS_AS_PRIMARY)) {
 		if (user_mode(regs))
 			return USER_FAULT;
-		if (!IS_ENABLED(CONFIG_PGSTE))
-			return KERNEL_FAULT;
-		if (test_pt_regs_flag(regs, PIF_GUEST_FAULT))
-			return GMAP_FAULT;
 		return KERNEL_FAULT;
 	}
 	if (teid.as == PSW_BITS_AS_SECONDARY)
@@ -184,10 +179,6 @@ static void dump_fault_info(struct pt_regs *regs)
 		asce = get_lowcore()->user_asce.val;
 		pr_cont("user ");
 		break;
-	case GMAP_FAULT:
-		asce = regs->cr1;
-		pr_cont("gmap ");
-		break;
 	case KERNEL_FAULT:
 		asce = get_lowcore()->kernel_asce.val;
 		pr_cont("kernel ");
@@ -285,7 +276,6 @@ static void do_exception(struct pt_regs *regs, int access)
 	struct mm_struct *mm;
 	enum fault_type type;
 	unsigned int flags;
-	struct gmap *gmap;
 	vm_fault_t fault;
 	bool is_write;
 
@@ -304,7 +294,6 @@ static void do_exception(struct pt_regs *regs, int access)
 	case KERNEL_FAULT:
 		return handle_fault_error_nolock(regs, 0);
 	case USER_FAULT:
-	case GMAP_FAULT:
 		if (faulthandler_disabled() || !mm)
 			return handle_fault_error_nolock(regs, 0);
 		break;
@@ -348,18 +337,6 @@ static void do_exception(struct pt_regs *regs, int access)
 	}
 lock_mmap:
 	mmap_read_lock(mm);
-	gmap = NULL;
-	if (IS_ENABLED(CONFIG_PGSTE) && type == GMAP_FAULT) {
-		gmap = (struct gmap *)get_lowcore()->gmap;
-		current->thread.gmap_addr = address;
-		current->thread.gmap_write_flag = !!(flags & FAULT_FLAG_WRITE);
-		current->thread.gmap_int_code = regs->int_code & 0xffff;
-		address = __gmap_translate(gmap, address);
-		if (address == -EFAULT)
-			return handle_fault_error(regs, SEGV_MAPERR);
-		if (gmap->pfault_enabled)
-			flags |= FAULT_FLAG_RETRY_NOWAIT;
-	}
 retry:
 	vma = find_vma(mm, address);
 	if (!vma)
@@ -375,50 +352,22 @@ retry:
 		return handle_fault_error(regs, SEGV_ACCERR);
 	fault = handle_mm_fault(vma, address, flags, regs);
 	if (fault_signal_pending(fault, regs)) {
-		if (flags & FAULT_FLAG_RETRY_NOWAIT)
-			mmap_read_unlock(mm);
 		if (!user_mode(regs))
 			handle_fault_error_nolock(regs, 0);
 		return;
 	}
 	/* The fault is fully completed (including releasing mmap lock) */
-	if (fault & VM_FAULT_COMPLETED) {
-		if (gmap) {
-			mmap_read_lock(mm);
-			goto gmap;
-		}
+	if (fault & VM_FAULT_COMPLETED)
 		return;
-	}
 	if (unlikely(fault & VM_FAULT_ERROR)) {
 		mmap_read_unlock(mm);
 		goto error;
 	}
 	if (fault & VM_FAULT_RETRY) {
-		if (IS_ENABLED(CONFIG_PGSTE) && gmap &&	(flags & FAULT_FLAG_RETRY_NOWAIT)) {
-			/*
-			 * FAULT_FLAG_RETRY_NOWAIT has been set,
-			 * mmap_lock has not been released
-			 */
-			current->thread.gmap_pfault = 1;
-			return handle_fault_error(regs, 0);
-		}
-		flags &= ~FAULT_FLAG_RETRY_NOWAIT;
 		flags |= FAULT_FLAG_TRIED;
 		mmap_read_lock(mm);
 		goto retry;
 	}
-gmap:
-	if (IS_ENABLED(CONFIG_PGSTE) && gmap) {
-		address =  __gmap_link(gmap, current->thread.gmap_addr,
-				       address);
-		if (address == -EFAULT)
-			return handle_fault_error(regs, SEGV_MAPERR);
-		if (address == -ENOMEM) {
-			fault = VM_FAULT_OOM;
-			mmap_read_unlock(mm);
-			goto error;
-		}
-	}
 	mmap_read_unlock(mm);
 	return;
 error:
@@ -494,7 +443,6 @@ void do_secure_storage_access(struct pt_regs *regs)
 	struct folio_walk fw;
 	struct mm_struct *mm;
 	struct folio *folio;
-	struct gmap *gmap;
 	int rc;
 
 	/*
@@ -520,15 +468,6 @@ void do_secure_storage_access(struct pt_regs *regs)
 		panic("Unexpected PGM 0x3d with TEID bit 61=0");
 	}
 	switch (get_fault_type(regs)) {
-	case GMAP_FAULT:
-		mm = current->mm;
-		gmap = (struct gmap *)get_lowcore()->gmap;
-		mmap_read_lock(mm);
-		addr = __gmap_translate(gmap, addr);
-		mmap_read_unlock(mm);
-		if (IS_ERR_VALUE(addr))
-			return handle_fault_error_nolock(regs, SEGV_MAPERR);
-		fallthrough;
 	case USER_FAULT:
 		mm = current->mm;
 		mmap_read_lock(mm);
@@ -564,40 +503,4 @@ void do_secure_storage_access(struct pt_regs *regs)
 }
 NOKPROBE_SYMBOL(do_secure_storage_access);
 
-void do_non_secure_storage_access(struct pt_regs *regs)
-{
-	struct gmap *gmap = (struct gmap *)get_lowcore()->gmap;
-	unsigned long gaddr = get_fault_address(regs);
-
-	if (WARN_ON_ONCE(get_fault_type(regs) != GMAP_FAULT))
-		return handle_fault_error_nolock(regs, SEGV_MAPERR);
-	if (gmap_convert_to_secure(gmap, gaddr) == -EINVAL)
-		send_sig(SIGSEGV, current, 0);
-}
-NOKPROBE_SYMBOL(do_non_secure_storage_access);
-
-void do_secure_storage_violation(struct pt_regs *regs)
-{
-	struct gmap *gmap = (struct gmap *)get_lowcore()->gmap;
-	unsigned long gaddr = get_fault_address(regs);
-
-	/*
-	 * If the VM has been rebooted, its address space might still contain
-	 * secure pages from the previous boot.
-	 * Clear the page so it can be reused.
-	 */
-	if (!gmap_destroy_page(gmap, gaddr))
-		return;
-	/*
-	 * Either KVM messed up the secure guest mapping or the same
-	 * page is mapped into multiple secure guests.
-	 *
-	 * This exception is only triggered when a guest 2 is running
-	 * and can therefore never occur in kernel context.
-	 */
-	pr_warn_ratelimited("Secure storage violation in task: %s, pid %d\n",
-			    current->comm, current->pid);
-	send_sig(SIGSEGV, current, 0);
-}
-
 #endif /* CONFIG_PGSTE */