From mboxrd@z Thu Jan 1 00:00:00 1970 From: Clément Léger Date: Tue, 14 May 2024 10:06:31 +0200 Subject: [RFC PATCH 5/7] riscv: add double trap driver In-Reply-To: References: <20240418142701.1493091-1-cleger@rivosinc.com> <20240418142701.1493091-6-cleger@rivosinc.com> Message-ID: List-Id: To: kvm-riscv@lists.infradead.org MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit On 27/04/2024 01:59, Deepak Gupta wrote: > On Thu, Apr 18, 2024 at 04:26:44PM +0200, Cl?ment L?ger wrote: >> Add a small driver to request double trap enabling as well as >> registering a SSE handler for double trap. This will also be used by KVM >> SBI FWFT extension support to detect if it is possible to enable double >> trap in VS-mode. >> >> Signed-off-by: Cl?ment L?ger >> --- >> arch/riscv/include/asm/sbi.h??? |? 1 + >> drivers/firmware/Kconfig??????? |? 7 +++ >> drivers/firmware/Makefile?????? |? 1 + >> drivers/firmware/riscv_dbltrp.c | 95 +++++++++++++++++++++++++++++++++ >> include/linux/riscv_dbltrp.h??? | 19 +++++++ >> 5 files changed, 123 insertions(+) >> create mode 100644 drivers/firmware/riscv_dbltrp.c >> create mode 100644 include/linux/riscv_dbltrp.h >> >> diff --git a/arch/riscv/include/asm/sbi.h b/arch/riscv/include/asm/sbi.h >> index 744aa1796c92..9cd4ca66487c 100644 >> --- a/arch/riscv/include/asm/sbi.h >> +++ b/arch/riscv/include/asm/sbi.h >> @@ -314,6 +314,7 @@ enum sbi_sse_attr_id { >> #define SBI_SSE_ATTR_INTERRUPTED_FLAGS_SPIE??? (1 << 2) >> >> #define SBI_SSE_EVENT_LOCAL_RAS??????? 0x00000000 >> +#define SBI_SSE_EVENT_LOCAL_DOUBLE_TRAP??? 0x00000001 >> #define SBI_SSE_EVENT_GLOBAL_RAS??? 0x00008000 >> #define SBI_SSE_EVENT_LOCAL_PMU??????? 0x00010000 >> #define SBI_SSE_EVENT_LOCAL_SOFTWARE??? 0xffff0000 >> diff --git a/drivers/firmware/Kconfig b/drivers/firmware/Kconfig >> index 59f611288807..a037f6e89942 100644 >> --- a/drivers/firmware/Kconfig >> +++ b/drivers/firmware/Kconfig >> @@ -197,6 +197,13 @@ config RISCV_SSE_TEST >> ????? Select if you want to enable SSE extension testing at boot time. >> ????? This will run a series of test which verifies SSE sanity. >> >> +config RISCV_DBLTRP >> +??? bool "Enable Double trap handling" >> +??? depends on RISCV_SSE && RISCV_SBI >> +??? default n >> +??? help >> +????? Select if you want to enable SSE double trap handler. >> + >> config SYSFB >> ????bool >> ????select BOOT_VESA_SUPPORT >> diff --git a/drivers/firmware/Makefile b/drivers/firmware/Makefile >> index fb7b0c08c56d..ad67a1738c0f 100644 >> --- a/drivers/firmware/Makefile >> +++ b/drivers/firmware/Makefile >> @@ -18,6 +18,7 @@ obj-$(CONFIG_RASPBERRYPI_FIRMWARE) += raspberrypi.o >> obj-$(CONFIG_FW_CFG_SYSFS)??? += qemu_fw_cfg.o >> obj-$(CONFIG_RISCV_SSE)??????? += riscv_sse.o >> obj-$(CONFIG_RISCV_SSE_TEST)??? += riscv_sse_test.o >> +obj-$(CONFIG_RISCV_DBLTRP)??? += riscv_dbltrp.o >> obj-$(CONFIG_SYSFB)??????? += sysfb.o >> obj-$(CONFIG_SYSFB_SIMPLEFB)??? += sysfb_simplefb.o >> obj-$(CONFIG_TI_SCI_PROTOCOL)??? += ti_sci.o >> diff --git a/drivers/firmware/riscv_dbltrp.c >> b/drivers/firmware/riscv_dbltrp.c >> new file mode 100644 >> index 000000000000..72f9a067e87a >> --- /dev/null >> +++ b/drivers/firmware/riscv_dbltrp.c >> @@ -0,0 +1,95 @@ >> +// SPDX-License-Identifier: GPL-2.0-only >> +/* >> + * Copyright (C) 2023 Rivos Inc. >> + */ > > nit: fix copyright year >> + >> +#define pr_fmt(fmt) "riscv-dbltrp: " fmt >> + >> +#include >> +#include >> +#include >> +#include >> + >> +#include >> + >> +static bool double_trap_enabled; >> + >> +static int riscv_sse_dbltrp_handle(uint32_t evt, void *arg, >> +?????????????????? struct pt_regs *regs) >> +{ >> +??? __show_regs(regs); >> +??? panic("Double trap !\n"); >> + >> +??? return 0; > Curious: > Does panic return? > What's the point of returning from here? Hi Deepak, No, panic() does not return and indeed, the "return 0" is useless. It's a leftover of a previous implementation without panic in order to keep GCC mouth shut ;). > >> +} >> + >> +struct cpu_dbltrp_data { >> +??? int error; >> +}; >> + >> +static void >> +sbi_cpu_enable_double_trap(void *data) >> +{ >> +??? struct sbiret ret; >> +??? struct cpu_dbltrp_data *cdd = data; >> + >> +??? ret = sbi_ecall(SBI_EXT_FWFT, SBI_EXT_FWFT_SET, >> +??????????? SBI_FWFT_DOUBLE_TRAP_ENABLE, 1, 0, 0, 0, 0); >> + >> +??? if (ret.error) { >> +??????? cdd->error = 1; >> +??????? pr_err("Failed to enable double trap on cpu %d\n", >> smp_processor_id()); >> +??? } >> +} >> + >> +static int sbi_enable_double_trap(void) >> +{ >> +??? struct cpu_dbltrp_data cdd = {0}; >> + >> +??? on_each_cpu(sbi_cpu_enable_double_trap, &cdd, 1); >> +??? if (cdd.error) >> +??????? return -1; > > There is a bug here. If `sbi_cpu_enable_double_trap` failed on all cpus > but last cpu. > Then cdd.error would not record error and will be reflect as if double > trap was enabled. cdd.error is only written in case of error by the per-cpu callbacks, so it is only set if enabled failed. Is there something I'm missing ? Thanks, Cl?ment > > Its less likely to happen that FW would return success for one cpu and > fail for others. > But there is non-zero probablity here. > From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id AC229C04FFE for ; Tue, 14 May 2024 08:06:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:References:Cc:To:Subject: From:MIME-Version:Date:Message-ID:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=nVylsh5jgs5mM2uPEfVGgeiY4eaB4n8Jsq/JK10w8QI=; b=Ox4NoLBwN68kNV Hd2AVGxkz4fxDE8QGsyeY1vixBi/BW8TwKsp3TtGjotbfmqI1IoCe8czEoG+GA9+0HIFKNPIvXV11 lZq3PQQPqBxV4gysPUVm4Wm770SXvAraYCyOsHgxzTfPpg2bLp8kdi+My8mANO4C2rP5NN0i2+o3U 0OrhZmk4uKrrwAgm4P8EpOAZkVD7gVrB5Vd3nN+rczRjSBExUvqVTRRwxelV1OMDxH61vSi3gVrUe KenkTvwjw2KBgBbhnS/rDCGN5Y5UTOhmf8QWAtxKzBBFgBPvaF2rTD/XlxGZBntyXXsWBFvUIVmpp +MbloRkGwmP+jecGtC9A==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1s6nBG-0000000FJ5v-1YKJ; Tue, 14 May 2024 08:06:38 +0000 Received: from mail-wm1-x329.google.com ([2a00:1450:4864:20::329]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1s6nBC-0000000FJ4x-1qTH for linux-riscv@lists.infradead.org; Tue, 14 May 2024 08:06:36 +0000 Received: by mail-wm1-x329.google.com with SMTP id 5b1f17b1804b1-420197fba0eso2035895e9.1 for ; Tue, 14 May 2024 01:06:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=rivosinc-com.20230601.gappssmtp.com; s=20230601; t=1715673992; x=1716278792; darn=lists.infradead.org; h=content-transfer-encoding:in-reply-to:content-language:references :cc:to:subject:from:user-agent:mime-version:date:message-id:from:to :cc:subject:date:message-id:reply-to; bh=pjopg8Hd6ezoM2VPeWMeiUlmhpM5PP4esFYOJITTIpM=; b=M903BIS0p0DekfgE87mGsWk9D8Jo9z/MuBow0nm98Vmdqc43XikjnIw1fy3Lz9v9qG eBt92i+rIQvbjCTgkiBvsD5FcxBCIUbunc69mQq2PjUXxUMWlt3gN/yvFs918cJ9bHdK QikOLxlgaTH65Rb7AUVa+77oHA2RguLcGJTf3AAzRFqcD3zhS2GK8bM0TyiaS4TWb4cZ irh3OLmKmWEhZELBqvKNUiWwRwgEMh9QrCT5IBOPqh9BTkrFbLNA/WE70XLdP9zOulNW DHZfbDZehhqFyHiHuQE2TZ0wv4aX1JA0RieNm+H8Hs5sC+9hdPGAOPxYPM0TWrDJ6ysq HE6Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1715673992; x=1716278792; h=content-transfer-encoding:in-reply-to:content-language:references :cc:to:subject:from:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=pjopg8Hd6ezoM2VPeWMeiUlmhpM5PP4esFYOJITTIpM=; b=tF32v/lGf6/7VI99cc1q+Sn6KLvvUFoliMad+J6C3yPXjzlphIHWdodlojdgVOpaEF SJLBIItYbSdLMdXBKL9a5lKY54GEWM+MDUhBVv/BzU7CZQ/m73HFPBR5Rk5SG2McPRTL S9BxUwkQgi6bPhamezxG11a6UrX50VMDOLGT+KATaGOHn+kiDt2YrUYEZik+4i+UzsYv +EhRj02k2nOBEJ89fw7KmrP99uV/KPNKndR8waOtaEEcxFT7POAH7vl20E/9b5uT8CVm uTB0CTg1/osAzmvf0f6gSyUQREduY+5xJmop6SQi11jF4iVvh+M2nB204DYPtFIZ0kvG ZEng== X-Forwarded-Encrypted: i=1; AJvYcCVlo7pczqL809vR1W1FRbi1/pyWu0OFlcZTfDTsHxohjL341tPgTVCjRvCYwz3azywb2kb1zVxKX7Z/A2i+v+eTT78yGM+kqfPJR1ALi/Zb X-Gm-Message-State: AOJu0Yz472NLSGX2X3ihDo10wpvs4HxsMlZwjq5TJfz1ARQwhVqUdXgR vvM2MqoN4sp0hiH98l7cI+HEpZtNXQtsWbWioDXU2fpN2EmGLKoqyL8ODnSzuuQ= X-Google-Smtp-Source: AGHT+IHrTYyJeDAN6oeeNkuklJ3k4rzrTPEj0NJCPsHETslMiuk4YMPVJXS8JcMds7tACAEYtoHs+w== X-Received: by 2002:adf:ff92:0:b0:34d:8ccf:c9ce with SMTP id ffacd0b85a97d-3504a967162mr8354223f8f.5.1715673992206; Tue, 14 May 2024 01:06:32 -0700 (PDT) Received: from ?IPV6:2a01:e0a:999:a3a0:1660:5f6e:2f9c:91b9? 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([2a01:e0a:999:a3a0:1660:5f6e:2f9c:91b9]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3502b896b0bsm13038230f8f.46.2024.05.14.01.06.31 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 14 May 2024 01:06:31 -0700 (PDT) Message-ID: Date: Tue, 14 May 2024 10:06:31 +0200 Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird From: =?UTF-8?B?Q2zDqW1lbnQgTMOpZ2Vy?= Subject: Re: [RFC PATCH 5/7] riscv: add double trap driver To: Deepak Gupta Cc: Conor Dooley , Rob Herring , Krzysztof Kozlowski , Paul Walmsley , Palmer Dabbelt , Albert Ou , Anup Patel , Atish Patra , linux-riscv@lists.infradead.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, kvm-riscv@lists.infradead.org, Ved Shanbhogue References: <20240418142701.1493091-1-cleger@rivosinc.com> <20240418142701.1493091-6-cleger@rivosinc.com> Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 27/04/2024 01:59, Deepak Gupta wrote: > On Thu, Apr 18, 2024 at 04:26:44PM +0200, Clément Léger wrote: >> Add a small driver to request double trap enabling as well as >> registering a SSE handler for double trap. This will also be used by KVM >> SBI FWFT extension support to detect if it is possible to enable double >> trap in VS-mode. >> >> Signed-off-by: Clément Léger >> --- >> arch/riscv/include/asm/sbi.h    |  1 + >> drivers/firmware/Kconfig        |  7 +++ >> drivers/firmware/Makefile       |  1 + >> drivers/firmware/riscv_dbltrp.c | 95 +++++++++++++++++++++++++++++++++ >> include/linux/riscv_dbltrp.h    | 19 +++++++ >> 5 files changed, 123 insertions(+) >> create mode 100644 drivers/firmware/riscv_dbltrp.c >> create mode 100644 include/linux/riscv_dbltrp.h >> >> diff --git a/arch/riscv/include/asm/sbi.h b/arch/riscv/include/asm/sbi.h >> index 744aa1796c92..9cd4ca66487c 100644 >> --- a/arch/riscv/include/asm/sbi.h >> +++ b/arch/riscv/include/asm/sbi.h >> @@ -314,6 +314,7 @@ enum sbi_sse_attr_id { >> #define SBI_SSE_ATTR_INTERRUPTED_FLAGS_SPIE    (1 << 2) >> >> #define SBI_SSE_EVENT_LOCAL_RAS        0x00000000 >> +#define SBI_SSE_EVENT_LOCAL_DOUBLE_TRAP    0x00000001 >> #define SBI_SSE_EVENT_GLOBAL_RAS    0x00008000 >> #define SBI_SSE_EVENT_LOCAL_PMU        0x00010000 >> #define SBI_SSE_EVENT_LOCAL_SOFTWARE    0xffff0000 >> diff --git a/drivers/firmware/Kconfig b/drivers/firmware/Kconfig >> index 59f611288807..a037f6e89942 100644 >> --- a/drivers/firmware/Kconfig >> +++ b/drivers/firmware/Kconfig >> @@ -197,6 +197,13 @@ config RISCV_SSE_TEST >>       Select if you want to enable SSE extension testing at boot time. >>       This will run a series of test which verifies SSE sanity. >> >> +config RISCV_DBLTRP >> +    bool "Enable Double trap handling" >> +    depends on RISCV_SSE && RISCV_SBI >> +    default n >> +    help >> +      Select if you want to enable SSE double trap handler. >> + >> config SYSFB >>     bool >>     select BOOT_VESA_SUPPORT >> diff --git a/drivers/firmware/Makefile b/drivers/firmware/Makefile >> index fb7b0c08c56d..ad67a1738c0f 100644 >> --- a/drivers/firmware/Makefile >> +++ b/drivers/firmware/Makefile >> @@ -18,6 +18,7 @@ obj-$(CONFIG_RASPBERRYPI_FIRMWARE) += raspberrypi.o >> obj-$(CONFIG_FW_CFG_SYSFS)    += qemu_fw_cfg.o >> obj-$(CONFIG_RISCV_SSE)        += riscv_sse.o >> obj-$(CONFIG_RISCV_SSE_TEST)    += riscv_sse_test.o >> +obj-$(CONFIG_RISCV_DBLTRP)    += riscv_dbltrp.o >> obj-$(CONFIG_SYSFB)        += sysfb.o >> obj-$(CONFIG_SYSFB_SIMPLEFB)    += sysfb_simplefb.o >> obj-$(CONFIG_TI_SCI_PROTOCOL)    += ti_sci.o >> diff --git a/drivers/firmware/riscv_dbltrp.c >> b/drivers/firmware/riscv_dbltrp.c >> new file mode 100644 >> index 000000000000..72f9a067e87a >> --- /dev/null >> +++ b/drivers/firmware/riscv_dbltrp.c >> @@ -0,0 +1,95 @@ >> +// SPDX-License-Identifier: GPL-2.0-only >> +/* >> + * Copyright (C) 2023 Rivos Inc. >> + */ > > nit: fix copyright year >> + >> +#define pr_fmt(fmt) "riscv-dbltrp: " fmt >> + >> +#include >> +#include >> +#include >> +#include >> + >> +#include >> + >> +static bool double_trap_enabled; >> + >> +static int riscv_sse_dbltrp_handle(uint32_t evt, void *arg, >> +                   struct pt_regs *regs) >> +{ >> +    __show_regs(regs); >> +    panic("Double trap !\n"); >> + >> +    return 0; > Curious: > Does panic return? > What's the point of returning from here? Hi Deepak, No, panic() does not return and indeed, the "return 0" is useless. It's a leftover of a previous implementation without panic in order to keep GCC mouth shut ;). > >> +} >> + >> +struct cpu_dbltrp_data { >> +    int error; >> +}; >> + >> +static void >> +sbi_cpu_enable_double_trap(void *data) >> +{ >> +    struct sbiret ret; >> +    struct cpu_dbltrp_data *cdd = data; >> + >> +    ret = sbi_ecall(SBI_EXT_FWFT, SBI_EXT_FWFT_SET, >> +            SBI_FWFT_DOUBLE_TRAP_ENABLE, 1, 0, 0, 0, 0); >> + >> +    if (ret.error) { >> +        cdd->error = 1; >> +        pr_err("Failed to enable double trap on cpu %d\n", >> smp_processor_id()); >> +    } >> +} >> + >> +static int sbi_enable_double_trap(void) >> +{ >> +    struct cpu_dbltrp_data cdd = {0}; >> + >> +    on_each_cpu(sbi_cpu_enable_double_trap, &cdd, 1); >> +    if (cdd.error) >> +        return -1; > > There is a bug here. If `sbi_cpu_enable_double_trap` failed on all cpus > but last cpu. > Then cdd.error would not record error and will be reflect as if double > trap was enabled. cdd.error is only written in case of error by the per-cpu callbacks, so it is only set if enabled failed. Is there something I'm missing ? Thanks, Clément > > Its less likely to happen that FW would return success for one cpu and > fail for others. > But there is non-zero probablity here. >