From b108f7f0a29b24a94e0c4f9af20f84afaa6ef245 Mon Sep 17 00:00:00 2001 From: Claudio Imbrenda Date: Tue, 28 Jun 2022 15:56:04 +0200 Subject: [PATCH] KVM: s390: pv: handle secure storage exceptions for normal guests With upcoming patches, normal guests might touch secure pages. This patch extends the existing exception handler to convert the pages to non secure also when the exception is triggered by a normal guest. This can happen for example when a secure guest reboots; the first stage of a secure guest is non secure, and in general a secure guest can reboot into non-secure mode. If the secure memory of the previous boot has not been cleared up completely yet (which will be allowed to happen in an upcoming patch), a non-secure guest might touch secure memory, which will need to be handled properly. This means that gmap faults must be handled and not cause termination of the process. The handling is the same as userspace accesses, it's enough to translate the gmap address to a user address and then let the normal user fault code handle it. Signed-off-by: Claudio Imbrenda Reviewed-by: Janosch Frank Link: https://lore.kernel.org/r/20220628135619.32410-4-imbrenda@linux.ibm.com Message-Id: <20220628135619.32410-4-imbrenda@linux.ibm.com> Signed-off-by: Janosch Frank --- arch/s390/mm/fault.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c index af1ac49168fb7..ee7871f770fb0 100644 --- a/arch/s390/mm/fault.c +++ b/arch/s390/mm/fault.c @@ -754,6 +754,7 @@ void do_secure_storage_access(struct pt_regs *regs) struct vm_area_struct *vma; struct mm_struct *mm; struct page *page; + struct gmap *gmap; int rc; /* @@ -783,6 +784,17 @@ void do_secure_storage_access(struct pt_regs *regs) } switch (get_fault_type(regs)) { + case GMAP_FAULT: + mm = current->mm; + gmap = (struct gmap *)S390_lowcore.gmap; + mmap_read_lock(mm); + addr = __gmap_translate(gmap, addr); + mmap_read_unlock(mm); + if (IS_ERR_VALUE(addr)) { + do_fault_error(regs, VM_ACCESS_FLAGS, VM_FAULT_BADMAP); + break; + } + fallthrough; case USER_FAULT: mm = current->mm; mmap_read_lock(mm); @@ -811,7 +823,6 @@ void do_secure_storage_access(struct pt_regs *regs) if (rc) BUG(); break; - case GMAP_FAULT: default: do_fault_error(regs, VM_READ | VM_WRITE, VM_FAULT_BADMAP); WARN_ON_ONCE(1); -- 2.30.2