KVM: s390: Backup the guest's machine check info

When a machine check happens in the guest, related mcck info (mcic,
external damage code, ...) is stored in the vcpu's lowcore on the host.
Then the machine check handler's low-level part is executed, followed
by the high-level part.

If the high-level part's execution is interrupted by a new machine check
happening on the same vcpu on the host, the mcck info in the lowcore is
overwritten with the new machine check's data.

If the high-level part's execution is scheduled to a different cpu,
the mcck info in the lowcore is uncertain.

Therefore, for both cases, the further reinjection to the guest will use
the wrong data.
Let's backup the mcck info in the lowcore to the sie page
for further reinjection, so that the right data will be used.

Add new member into struct sie_page to store related machine check's
info of mcic, failing storage address and external damage code.

Signed-off-by: QingFeng Hao <haoqf@linux.vnet.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

1 files changed, 34 insertions, 0 deletions

diff --git a/arch/s390/kernel/nmi.c b/arch/s390/kernel/nmi.c
index 958cc3352faa..31d03a84126c 100644
--- a/arch/s390/kernel/nmi.c
+++ b/arch/s390/kernel/nmi.c
@@ -26,6 +26,7 @@
 #include <asm/switch_to.h>
 #include <asm/ctl_reg.h>
 #include <asm/asm-offsets.h>
+#include <linux/kvm_host.h>
 
 struct mcck_struct {
 	unsigned int kill_task : 1;
@@ -275,6 +276,31 @@ static int notrace s390_validate_registers(union mci mci, int umode)
 	return kill_task;
 }
 
+/*
+ * Backup the guest's machine check info to its description block
+ */
+static void notrace s390_backup_mcck_info(struct pt_regs *regs)
+{
+	struct mcck_volatile_info *mcck_backup;
+	struct sie_page *sie_page;
+
+	/* r14 contains the sie block, which was set in sie64a */
+	struct kvm_s390_sie_block *sie_block =
+			(struct kvm_s390_sie_block *) regs->gprs[14];
+
+	if (sie_block == NULL)
+		/* Something's seriously wrong, stop system. */
+		s390_handle_damage();
+
+	sie_page = container_of(sie_block, struct sie_page, sie_block);
+	mcck_backup = &sie_page->mcck_info;
+	mcck_backup->mcic = S390_lowcore.mcck_interruption_code &
+				~(MCCK_CODE_CP | MCCK_CODE_EXT_DAMAGE);
+	mcck_backup->ext_damage_code = S390_lowcore.external_damage_code;
+	mcck_backup->failing_storage_address
+			= S390_lowcore.failing_storage_address;
+}
+
 #define MAX_IPD_COUNT	29
 #define MAX_IPD_TIME	(5 * 60 * USEC_PER_SEC) /* 5 minutes */
 
@@ -355,6 +381,14 @@ void notrace s390_do_machine_check(struct pt_regs *regs)
 		mcck->mcck_code = mci.val;
 		set_cpu_flag(CIF_MCCK_PENDING);
 	}
+
+	/*
+	 * Backup the machine check's info if it happens when the guest
+	 * is running.
+	 */
+	if (test_cpu_flag(CIF_MCCK_GUEST))
+		s390_backup_mcck_info(regs);
+
 	if (mci.cd) {
 		/* Timing facility damage */
 		s390_handle_damage();