s390/nmi: s390: New low level handling for machine check happening in guest

Add the logic to check if the machine check happens when the guest is
running. If yes, set the exit reason -EINTR in the machine check's
interrupt handler. Refactor s390_do_machine_check to avoid panicing
the host for some kinds of machine checks which happen
when guest is running.
Reinject the instruction processing damage's machine checks including
Delayed Access Exception instead of damaging the host if it happens
in the guest because it could be caused by improper update on TLB entry
or other software case and impacts the guest only.

Signed-off-by: QingFeng Hao <haoqf@linux.vnet.ibm.com>
Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

diff --git a/arch/s390/include/asm/nmi.h b/arch/s390/include/asm/nmi.h
index e3e8895f5d3ea36860c183304d412172d15ea46a..13623b9991d467ac542e8a5b444d6d9e1a72daa9 100644 (file)
--- a/arch/s390/include/asm/nmi.h
+++ b/arch/s390/include/asm/nmi.h
@@ -14,7 +14,14 @@
 #include <linux/const.h>
 #include <linux/types.h>
 
+#define MCIC_SUBCLASS_MASK     (1ULL<<63 | 1ULL<<62 | 1ULL<<61 | \
+                               1ULL<<59 | 1ULL<<58 | 1ULL<<56 | \
+                               1ULL<<55 | 1ULL<<54 | 1ULL<<53 | \
+                               1ULL<<52 | 1ULL<<47 | 1ULL<<46 | \
+                               1ULL<<45 | 1ULL<<44)
 #define MCCK_CODE_SYSTEM_DAMAGE                _BITUL(63)
+#define MCCK_CODE_EXT_DAMAGE           _BITUL(63 - 5)
+#define MCCK_CODE_CP                   _BITUL(63 - 9)
 #define MCCK_CODE_CPU_TIMER_VALID      _BITUL(63 - 46)
 #define MCCK_CODE_PSW_MWP_VALID                _BITUL(63 - 20)
 #define MCCK_CODE_PSW_IA_VALID         _BITUL(63 - 23)

diff --git a/arch/s390/include/asm/processor.h b/arch/s390/include/asm/processor.h
index 60d395fdc86438e55f49ddf853dca7b6f99582b3..5b1b247dfbca0dc9d08feb060486ce1471a85778 100644 (file)
--- a/arch/s390/include/asm/processor.h
+++ b/arch/s390/include/asm/processor.h
@@ -20,6 +20,7 @@
 #define CIF_FPU                        4       /* restore FPU registers */
 #define CIF_IGNORE_IRQ         5       /* ignore interrupt (for udelay) */
 #define CIF_ENABLED_WAIT       6       /* in enabled wait state */
+#define CIF_MCCK_GUEST         7       /* machine check happening in guest */
 
 #define _CIF_MCCK_PENDING      _BITUL(CIF_MCCK_PENDING)
 #define _CIF_ASCE_PRIMARY      _BITUL(CIF_ASCE_PRIMARY)
@@ -28,6 +29,7 @@
 #define _CIF_FPU               _BITUL(CIF_FPU)
 #define _CIF_IGNORE_IRQ                _BITUL(CIF_IGNORE_IRQ)
 #define _CIF_ENABLED_WAIT      _BITUL(CIF_ENABLED_WAIT)
+#define _CIF_MCCK_GUEST                _BITUL(CIF_MCCK_GUEST)
 
 #ifndef __ASSEMBLY__
 

diff --git a/arch/s390/kernel/asm-offsets.c b/arch/s390/kernel/asm-offsets.c
index 6bb29633e1f1b701aa1b8737339c350f45e65464..b65c414b6c0e030cecb4bdb8fb074fa935c769df 100644 (file)
--- a/arch/s390/kernel/asm-offsets.c
+++ b/arch/s390/kernel/asm-offsets.c
@@ -58,6 +58,9 @@ int main(void)
        OFFSET(__SF_BACKCHAIN, stack_frame, back_chain);
        OFFSET(__SF_GPRS, stack_frame, gprs);
        OFFSET(__SF_EMPTY, stack_frame, empty1);
+       OFFSET(__SF_SIE_CONTROL, stack_frame, empty1[0]);
+       OFFSET(__SF_SIE_SAVEAREA, stack_frame, empty1[1]);
+       OFFSET(__SF_SIE_REASON, stack_frame, empty1[2]);
        BLANK();
        /* timeval/timezone offsets for use by vdso */
        OFFSET(__VDSO_UPD_COUNT, vdso_data, tb_update_count);

diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S
index a5f5d3bb3dbc516d23c98082d0f3abe186fc95c1..9b48196ebf4057bf1a6ba0c8a86539f28d06e759 100644 (file)
--- a/arch/s390/kernel/entry.S
+++ b/arch/s390/kernel/entry.S
@@ -225,6 +225,7 @@ ENTRY(sie64a)
        jnz     .Lsie_skip
        TSTMSK  __LC_CPU_FLAGS,_CIF_FPU
        jo      .Lsie_skip                      # exit if fp/vx regs changed
+.Lsie_entry:
        sie     0(%r14)
 .Lsie_skip:
        ni      __SIE_PROG0C+3(%r14),0xfe       # no longer in SIE
@@ -1102,7 +1103,13 @@ cleanup_critical:
        .quad   .Lsie_done
 
 .Lcleanup_sie:
-       lg      %r9,__SF_EMPTY(%r15)            # get control block pointer
+       cghi    %r11,__LC_SAVE_AREA_ASYNC       #Is this in normal interrupt?
+       je      1f
+       slg     %r9,BASED(.Lsie_crit_mcck_start)
+       clg     %r9,BASED(.Lsie_crit_mcck_length)
+       jh      1f
+       oi      __LC_CPU_FLAGS+7, _CIF_MCCK_GUEST
+1:     lg      %r9,__SF_EMPTY(%r15)            # get control block pointer
        ni      __SIE_PROG0C+3(%r9),0xfe        # no longer in SIE
        lctlg   %c1,%c1,__LC_USER_ASCE          # load primary asce
        larl    %r9,sie_exit                    # skip forward to sie_exit
@@ -1274,6 +1281,10 @@ cleanup_critical:
        .quad   .Lsie_gmap
 .Lsie_critical_length:
        .quad   .Lsie_done - .Lsie_gmap
+.Lsie_crit_mcck_start:
+       .quad   .Lsie_entry
+.Lsie_crit_mcck_length:
+       .quad   .Lsie_skip - .Lsie_entry
 #endif
 
        .section .rodata, "a"

diff --git a/arch/s390/kernel/nmi.c b/arch/s390/kernel/nmi.c
index 9855895239704f10deedaeff259edc5279a01519..958cc3352faa4bdaf044ee45e71767fb0bc7f718 100644 (file)
--- a/arch/s390/kernel/nmi.c
+++ b/arch/s390/kernel/nmi.c
@@ -25,6 +25,7 @@
 #include <asm/crw.h>
 #include <asm/switch_to.h>
 #include <asm/ctl_reg.h>
+#include <asm/asm-offsets.h>
 
 struct mcck_struct {
        unsigned int kill_task : 1;
@@ -280,6 +281,8 @@ static int notrace s390_validate_registers(union mci mci, int umode)
 #define ED_STP_ISLAND  6       /* External damage STP island check */
 #define ED_STP_SYNC    7       /* External damage STP sync check */
 
+#define MCCK_CODE_NO_GUEST     (MCCK_CODE_CP | MCCK_CODE_EXT_DAMAGE)
+
 /*
  * machine check handler.
  */
@@ -291,6 +294,7 @@ void notrace s390_do_machine_check(struct pt_regs *regs)
        struct mcck_struct *mcck;
        unsigned long long tmp;
        union mci mci;
+       unsigned long mcck_dam_code;
 
        nmi_enter();
        inc_irq_stat(NMI_NMI);
@@ -301,7 +305,13 @@ void notrace s390_do_machine_check(struct pt_regs *regs)
                /* System damage -> stopping machine */
                s390_handle_damage();
        }
-       if (mci.pd) {
+
+       /*
+        * Reinject the instruction processing damages' machine checks
+        * including Delayed Access Exception into the guest
+        * instead of damaging the host if they happen in the guest.
+        */
+       if (mci.pd && !test_cpu_flag(CIF_MCCK_GUEST)) {
                if (mci.b) {
                        /* Processing backup -> verify if we can survive this */
                        u64 z_mcic, o_mcic, t_mcic;
@@ -358,15 +368,22 @@ void notrace s390_do_machine_check(struct pt_regs *regs)
                if (mcck->stp_queue)
                        set_cpu_flag(CIF_MCCK_PENDING);
        }
-       if (mci.se)
-               /* Storage error uncorrected */
-               s390_handle_damage();
-       if (mci.ke)
-               /* Storage key-error uncorrected */
-               s390_handle_damage();
-       if (mci.ds && mci.fa)
-               /* Storage degradation */
-               s390_handle_damage();
+
+       /*
+        * Reinject storage related machine checks into the guest if they
+        * happen when the guest is running.
+        */
+       if (!test_cpu_flag(CIF_MCCK_GUEST)) {
+               if (mci.se)
+                       /* Storage error uncorrected */
+                       s390_handle_damage();
+               if (mci.ke)
+                       /* Storage key-error uncorrected */
+                       s390_handle_damage();
+               if (mci.ds && mci.fa)
+                       /* Storage degradation */
+                       s390_handle_damage();
+       }
        if (mci.cp) {
                /* Channel report word pending */
                mcck->channel_report = 1;
@@ -377,6 +394,19 @@ void notrace s390_do_machine_check(struct pt_regs *regs)
                mcck->warning = 1;
                set_cpu_flag(CIF_MCCK_PENDING);
        }
+
+       /*
+        * If there are only Channel Report Pending and External Damage
+        * machine checks, they will not be reinjected into the guest
+        * because they refer to host conditions only.
+        */
+       mcck_dam_code = (mci.val & MCIC_SUBCLASS_MASK);
+       if (test_cpu_flag(CIF_MCCK_GUEST) &&
+       (mcck_dam_code & MCCK_CODE_NO_GUEST) != mcck_dam_code) {
+               /* Set exit reason code for host's later handling */
+               *((long *)(regs->gprs[15] + __SF_SIE_REASON)) = -EINTR;
+       }
+       clear_cpu_flag(CIF_MCCK_GUEST);
        nmi_exit();
 }