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From: Ganesh Goudar <ganeshgr@linux.ibm.com>
To: linuxppc-dev@lists.ozlabs.org, mpe@ellerman.id.au
Cc: msuchanek@suse.de, Ganesh Goudar <ganeshgr@linux.ibm.com>,
	keescook@chromium.org, npiggin@gmail.com, mahesh@linux.ibm.com
Subject: [PATCH v4 1/2] powerpc/mce: remove nmi_enter/exit from real mode handler
Date: Fri,  9 Oct 2020 12:10:04 +0530
Message-ID: <20201009064005.19777-2-ganeshgr@linux.ibm.com> (raw)
In-Reply-To: <20201009064005.19777-1-ganeshgr@linux.ibm.com>

Use of nmi_enter/exit in real mode handler causes the kernel to panic
and reboot on injecting slb mutihit on pseries machine running in hash
mmu mode, As these calls try to accesses memory outside RMO region in
real mode handler where translation is disabled.

Add check to not to use these calls on pseries machine running in hash
mmu mode.

Fixes: 116ac378bb3f ("powerpc/64s: machine check interrupt update NMI accounting")
Signed-off-by: Ganesh Goudar <ganeshgr@linux.ibm.com>
---
 arch/powerpc/kernel/mce.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/kernel/mce.c b/arch/powerpc/kernel/mce.c
index ada59f6c4298..63702c0badb9 100644
--- a/arch/powerpc/kernel/mce.c
+++ b/arch/powerpc/kernel/mce.c
@@ -591,12 +591,11 @@ EXPORT_SYMBOL_GPL(machine_check_print_event_info);
 long notrace machine_check_early(struct pt_regs *regs)
 {
 	long handled = 0;
-	bool nested = in_nmi();
 	u8 ftrace_enabled = this_cpu_get_ftrace_enabled();
 
 	this_cpu_set_ftrace_enabled(0);
-
-	if (!nested)
+	/* Do not use nmi_enter/exit for pseries hpte guest */
+	if (radix_enabled() || !firmware_has_feature(FW_FEATURE_LPAR))
 		nmi_enter();
 
 	hv_nmi_check_nonrecoverable(regs);
@@ -607,7 +606,7 @@ long notrace machine_check_early(struct pt_regs *regs)
 	if (ppc_md.machine_check_early)
 		handled = ppc_md.machine_check_early(regs);
 
-	if (!nested)
+	if (radix_enabled() || !firmware_has_feature(FW_FEATURE_LPAR))
 		nmi_exit();
 
 	this_cpu_set_ftrace_enabled(ftrace_enabled);
-- 
2.26.2


  reply index

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-09  6:40 [PATCH v4 0/2] powerpc/mce: Fix mce handler and add selftest Ganesh Goudar
2020-10-09  6:40 ` Ganesh Goudar [this message]
2020-10-09  6:40 ` [PATCH v4 2/2] lkdtm/powerpc: Add SLB multihit test Ganesh Goudar
2020-10-19 10:59   ` Michael Ellerman
2020-10-19 13:15     ` Michal Suchánek
2020-11-26 13:27       ` Ganesh
2020-10-16 11:32 ` [PATCH v4 0/2] powerpc/mce: Fix mce handler and add selftest Michael Ellerman
2020-10-19  5:26   ` Ganesh

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