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[61.68.214.199]) by smtp.gmail.com with ESMTPSA id i9sm358813pfk.199.2020.05.07.21.34.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 07 May 2020 21:34:42 -0700 (PDT) From: Nicholas Piggin To: linuxppc-dev@lists.ozlabs.org Subject: [PATCH v4 11/16] powerpc/64s: machine check interrupt update NMI accounting Date: Fri, 8 May 2020 14:34:03 +1000 Message-Id: <20200508043408.886394-12-npiggin@gmail.com> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20200508043408.886394-1-npiggin@gmail.com> References: <20200508043408.886394-1-npiggin@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Nicholas Piggin Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" machine_check_early is taken as an NMI, so nmi_enter is used there. machine_check_exception is no longer taken as an NMI (it's invoked via irq_work in the case a machine check hits in kernel mode), so remove the nmi_enter from that case. In NMI context, hash faults don't try to refill the hash table, which can lead to crashes accessing non-pinned kernel pages. System reset still has this potential problem. Signed-off-by: Nicholas Piggin --- arch/powerpc/kernel/mce.c | 7 +++++++ arch/powerpc/kernel/process.c | 2 +- arch/powerpc/kernel/traps.c | 14 +++++++++++++- 3 files changed, 21 insertions(+), 2 deletions(-) diff --git a/arch/powerpc/kernel/mce.c b/arch/powerpc/kernel/mce.c index 8077b5fb18a7..be7e3f92a7b5 100644 --- a/arch/powerpc/kernel/mce.c +++ b/arch/powerpc/kernel/mce.c @@ -574,6 +574,9 @@ EXPORT_SYMBOL_GPL(machine_check_print_event_info); long machine_check_early(struct pt_regs *regs) { long handled = 0; + bool nested = in_nmi(); + if (!nested) + nmi_enter(); hv_nmi_check_nonrecoverable(regs); @@ -582,6 +585,10 @@ long machine_check_early(struct pt_regs *regs) */ if (ppc_md.machine_check_early) handled = ppc_md.machine_check_early(regs); + + if (!nested) + nmi_exit(); + return handled; } diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c index 9c21288f8645..44410dd3029f 100644 --- a/arch/powerpc/kernel/process.c +++ b/arch/powerpc/kernel/process.c @@ -1421,7 +1421,7 @@ void show_regs(struct pt_regs * regs) pr_cont("DAR: "REG" DSISR: %08lx ", regs->dar, regs->dsisr); #endif #ifdef CONFIG_PPC64 - pr_cont("IRQMASK: %lx ", regs->softe); + pr_cont("IRQMASK: %lx IN_NMI:%d IN_MCE:%d", regs->softe, (int)get_paca()->in_nmi, (int)get_paca()->in_mce); #endif #ifdef CONFIG_PPC_TRANSACTIONAL_MEM if (MSR_TM_ACTIVE(regs->msr)) diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c index 3fca22276bb1..9f6852322e59 100644 --- a/arch/powerpc/kernel/traps.c +++ b/arch/powerpc/kernel/traps.c @@ -823,7 +823,19 @@ int machine_check_generic(struct pt_regs *regs) void machine_check_exception(struct pt_regs *regs) { int recover = 0; - bool nested = in_nmi(); + bool nested; + + /* + * BOOK3S_64 does not call this handler as a non-maskable interrupt + * (it uses its own early real-mode handler to handle the MCE proper + * and then raises irq_work to call this handler when interrupts are + * enabled). Set nested = true for this case, which just makes it avoid + * the nmi_enter/exit. + */ + if (IS_ENABLED(CONFIG_PPC_BOOK3S_64) || in_nmi()) + nested = true; + else + nested = false; if (!nested) nmi_enter(); -- 2.23.0