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Fri, 16 Oct 2020 08:53:53 +0000 (UTC) Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 92038ADE8; Fri, 16 Oct 2020 08:53:52 +0000 (UTC) X-Outflank-Mailman: Message body and most headers restored to incoming version X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: 0514ee4d-f27f-4eec-91c8-876f51d5a0c1 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1602838432; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=zyQ6eY76TMGPa8WVIau7vgU5vO2lNHpIxzzWhjQGo/o=; b=BZLrBXjW2NcVN4gnBUmmQWXJtGnOha8usIRFFMsQ2VKj+cEPtjvMRMe+WLRCvluBZBmLsv Mii/naLC/ClGU3oocMpFgwxQ7VGuXUPGEGb2b5Fvpx+5gFEimK2aYGzlnT9/rxIA/zVZIY MIeL9jIWDa6bq+svRUamZlH99qnEcUM= From: Juergen Gross To: xen-devel@lists.xenproject.org Cc: Juergen Gross , Jan Beulich , Andrew Cooper , =?UTF-8?q?Roger=20Pau=20Monn=C3=A9?= , Wei Liu Subject: [PATCH v3 1/3] xen/x86: add nmi continuation framework Date: Fri, 16 Oct 2020 10:53:48 +0200 Message-Id: <20201016085350.10233-2-jgross@suse.com> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20201016085350.10233-1-jgross@suse.com> References: <20201016085350.10233-1-jgross@suse.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-ZohoMail-DKIM: pass (identity @suse.com) Actions in NMI context are rather limited as e.g. locking is rather fragile. Add a generic framework to continue processing in normal interrupt context after leaving NMI processing. This is done by a high priority interrupt vector triggered via a self IPI from NMI context, which will then call the continuation function specified during NMI handling. Signed-off-by: Juergen Gross --- V2: - add prototype for continuation function (Roger Pau Monn=C3=A9) - switch from softirq to explicit self-IPI (Jan Beulich) --- xen/arch/x86/apic.c | 13 +++++++--- xen/arch/x86/traps.c | 52 +++++++++++++++++++++++++++++++++++++++ xen/include/asm-x86/nmi.h | 13 +++++++++- 3 files changed, 74 insertions(+), 4 deletions(-) diff --git a/xen/arch/x86/apic.c b/xen/arch/x86/apic.c index 60627fd6e6..7497ddb5da 100644 --- a/xen/arch/x86/apic.c +++ b/xen/arch/x86/apic.c @@ -40,6 +40,7 @@ #include #include #include +#include #include =20 static bool __read_mostly tdt_enabled; @@ -1376,16 +1377,22 @@ void spurious_interrupt(struct cpu_user_regs *regs) { /* * Check if this is a vectored interrupt (most likely, as this is prob= ably - * a request to dump local CPU state). Vectored interrupts are ACKed; - * spurious interrupts are not. + * a request to dump local CPU state or to continue NMI handling). + * Vectored interrupts are ACKed; spurious interrupts are not. */ if (apic_isr_read(SPURIOUS_APIC_VECTOR)) { + bool is_spurious; + ack_APIC_irq(); + is_spurious =3D !nmi_check_continuation(); if (this_cpu(state_dump_pending)) { this_cpu(state_dump_pending) =3D false; dump_execstate(regs); - return; + is_spurious =3D false; } + + if ( !is_spurious ) + return; } =20 /* see sw-dev-man vol 3, chapter 7.4.13.5 */ diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c index bc5b8f8ea3..6f4db9d549 100644 --- a/xen/arch/x86/traps.c +++ b/xen/arch/x86/traps.c @@ -79,6 +79,7 @@ #include #include #include +#include #include #include =20 @@ -1799,6 +1800,57 @@ void unset_nmi_callback(void) nmi_callback =3D dummy_nmi_callback; } =20 +static DEFINE_PER_CPU(nmi_contfunc_t *, nmi_cont_func); +static DEFINE_PER_CPU(void *, nmi_cont_arg); +static DEFINE_PER_CPU(bool, nmi_cont_busy); + +bool nmi_check_continuation(void) +{ + unsigned int cpu =3D smp_processor_id(); + nmi_contfunc_t *func =3D per_cpu(nmi_cont_func, cpu); + void *arg =3D per_cpu(nmi_cont_arg, cpu); + + if ( per_cpu(nmi_cont_busy, cpu) ) + { + per_cpu(nmi_cont_busy, cpu) =3D false; + printk("Trying to set NMI continuation while still one active!\n"); + } + + /* Reads must be done before following write (local cpu ordering only)= . */ + barrier(); + + per_cpu(nmi_cont_func, cpu) =3D NULL; + + if ( func ) + func(arg); + + return func; +} + +int set_nmi_continuation(nmi_contfunc_t *func, void *arg) +{ + unsigned int cpu =3D smp_processor_id(); + + if ( per_cpu(nmi_cont_func, cpu) ) + { + per_cpu(nmi_cont_busy, cpu) =3D true; + return -EBUSY; + } + + per_cpu(nmi_cont_func, cpu) =3D func; + per_cpu(nmi_cont_arg, cpu) =3D arg; + + /* + * Issue a self-IPI. Handling is done in spurious_interrupt(). + * NMI could have happened in IPI sequence, so wait for ICR being idle + * again before leaving NMI handler. + */ + send_IPI_self(SPURIOUS_APIC_VECTOR); + apic_wait_icr_idle(); + + return 0; +} + void do_device_not_available(struct cpu_user_regs *regs) { #ifdef CONFIG_PV diff --git a/xen/include/asm-x86/nmi.h b/xen/include/asm-x86/nmi.h index a288f02a50..68db75b1ed 100644 --- a/xen/include/asm-x86/nmi.h +++ b/xen/include/asm-x86/nmi.h @@ -33,5 +33,16 @@ nmi_callback_t *set_nmi_callback(nmi_callback_t *callbac= k); void unset_nmi_callback(void); =20 DECLARE_PER_CPU(unsigned int, nmi_count); -=20 + +typedef void nmi_contfunc_t(void *arg); + +/** + * set_nmi_continuation + * + * Schedule a function to be started in interrupt context after NMI handli= ng. + */ +int set_nmi_continuation(nmi_contfunc_t *func, void *arg); + +/* Check for NMI continuation pending. */ +bool nmi_check_continuation(void); #endif /* ASM_NMI_H */ --=20 2.26.2