From: Janosch Frank frankja@linux.ibm.com
commit cd4d3d5f21ddbfae3f686ac0ff405f21f7847ad3 upstream.
Program exception 3f (secure storage violation) can only be detected when the CPU is running in SIE with a format 4 state description, e.g. running a protected guest. Because of this and because user space partly controls the guest memory mapping and can trigger this exception, we want to send a SIGSEGV to the process running the guest and not panic the kernel.
Signed-off-by: Janosch Frank frankja@linux.ibm.com Cc: stable@vger.kernel.org # 5.7 Fixes: 084ea4d611a3 ("s390/mm: add (non)secure page access exceptions handlers") Reviewed-by: Claudio Imbrenda imbrenda@linux.ibm.com Reviewed-by: Cornelia Huck cohuck@redhat.com Acked-by: Christian Borntraeger borntraeger@de.ibm.com Signed-off-by: Heiko Carstens hca@linux.ibm.com Signed-off-by: Vasily Gorbik gor@linux.ibm.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/s390/kernel/entry.h | 1 + arch/s390/kernel/pgm_check.S | 2 +- arch/s390/mm/fault.c | 20 ++++++++++++++++++++ 3 files changed, 22 insertions(+), 1 deletion(-)
--- a/arch/s390/kernel/entry.h +++ b/arch/s390/kernel/entry.h @@ -26,6 +26,7 @@ void do_protection_exception(struct pt_r void do_dat_exception(struct pt_regs *regs); void do_secure_storage_access(struct pt_regs *regs); void do_non_secure_storage_access(struct pt_regs *regs); +void do_secure_storage_violation(struct pt_regs *regs);
void addressing_exception(struct pt_regs *regs); void data_exception(struct pt_regs *regs); --- a/arch/s390/kernel/pgm_check.S +++ b/arch/s390/kernel/pgm_check.S @@ -80,7 +80,7 @@ PGM_CHECK(do_dat_exception) /* 3b */ PGM_CHECK_DEFAULT /* 3c */ PGM_CHECK(do_secure_storage_access) /* 3d */ PGM_CHECK(do_non_secure_storage_access) /* 3e */ -PGM_CHECK_DEFAULT /* 3f */ +PGM_CHECK(do_secure_storage_violation) /* 3f */ PGM_CHECK(monitor_event_exception) /* 40 */ PGM_CHECK_DEFAULT /* 41 */ PGM_CHECK_DEFAULT /* 42 */ --- a/arch/s390/mm/fault.c +++ b/arch/s390/mm/fault.c @@ -875,6 +875,21 @@ void do_non_secure_storage_access(struct } NOKPROBE_SYMBOL(do_non_secure_storage_access);
+void do_secure_storage_violation(struct pt_regs *regs) +{ + /* + * 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. + */ + printk_ratelimited(KERN_WARNING + "Secure storage violation in task: %s, pid %d\n", + current->comm, current->pid); + send_sig(SIGSEGV, current, 0); +} + #else void do_secure_storage_access(struct pt_regs *regs) { @@ -885,4 +900,9 @@ void do_non_secure_storage_access(struct { default_trap_handler(regs); } + +void do_secure_storage_violation(struct pt_regs *regs) +{ + default_trap_handler(regs); +} #endif