From patchwork Tue Apr 9 19:22:16 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Murray X-Patchwork-Id: 10892181 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id BCD92922 for ; Tue, 9 Apr 2019 19:23:42 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id A51012890C for ; Tue, 9 Apr 2019 19:23:42 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 9955428938; Tue, 9 Apr 2019 19:23:42 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 2447F2890C for ; Tue, 9 Apr 2019 19:23:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=Manpg4/B1ZYVNnDpNtCb03SD2vAH1UcGq2dwjsICFT8=; b=I3JNo3VE0p11OI qTquaHHhPT8oazMWsxTOMDT3ES+dQeOXX2qW1p08a0NKjuXrj2CnRFOqemtVnkCH+ZRqXeRV2dMBY olcm1svanXw2vuRel+J4q1g3/sKd4bHo98fOGXVVi6dtdOrrLhwMhEIYtA6T0aGCTsltR6uV53ZqG f8OxmqwD4lk/Apj28qRlsTiW6s/ZpHfmuHagRGx3jx1s4TDuVjvKuhB3JZs1cojB6sh2yzljmovTk V2CinSMPu8hJcA7+6E3U2IfTDWLYF9KOU3P4dCVktUJxwKkl5UPLQIZNhpFAPYjDiOqyeMJgaDR1v jjZ7lTdv9NS7s/+owQdw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1hDwLH-0006gO-4w; Tue, 09 Apr 2019 19:23:35 +0000 Received: from foss.arm.com ([217.140.101.70]) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1hDwKO-0005YK-TX for linux-arm-kernel@lists.infradead.org; Tue, 09 Apr 2019 19:22:48 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 94A781688; Tue, 9 Apr 2019 12:22:40 -0700 (PDT) Received: from e119886-lin.cambridge.arm.com (unknown [10.37.6.20]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 9C7803F59C; Tue, 9 Apr 2019 12:22:38 -0700 (PDT) From: Andrew Murray To: Christoffer Dall , Marc Zyngier , Catalin Marinas , Will Deacon , Mark Rutland Subject: [PATCH v13 7/8] arm64: KVM: avoid isb's by using direct pmxevtyper sysreg Date: Tue, 9 Apr 2019 20:22:16 +0100 Message-Id: <20190409192217.23459-8-andrew.murray@arm.com> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190409192217.23459-1-andrew.murray@arm.com> References: <20190409192217.23459-1-andrew.murray@arm.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190409_122241_640364_68838681 X-CRM114-Status: GOOD ( 16.59 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Julien Thierry , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org, Suzuki K Poulose Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP Upon entering or exiting a guest we may modify multiple PMU counters to enable of disable EL0 filtering. We presently do this via the indirect PMXEVTYPER_EL0 system register (where the counter we modify is selected by PMSELR). With this approach it is necessary to order the writes via isb instructions such that we select the correct counter before modifying it. Let's avoid potentially expensive instruction barriers by using the direct PMEVTYPER_EL0 registers instead. As the change to counter type relates only to EL0 filtering we can rely on the implicit instruction barrier which occurs when we transition from EL2 to EL1 on entering the guest. On returning to userspace we can, at the latest, rely on the implicit barrier between EL2 and EL0. We can also depend on the explicit isb in armv8pmu_select_counter to order our write against any other kernel changes by the PMU driver to the type register as a result of preemption. Signed-off-by: Andrew Murray Reviewed-by: Suzuki K Poulose --- arch/arm64/kvm/pmu.c | 84 ++++++++++++++++++++++++++++++++++++++------ 1 file changed, 74 insertions(+), 10 deletions(-) diff --git a/arch/arm64/kvm/pmu.c b/arch/arm64/kvm/pmu.c index 3407a529e116..4d55193ccc71 100644 --- a/arch/arm64/kvm/pmu.c +++ b/arch/arm64/kvm/pmu.c @@ -91,6 +91,74 @@ void __hyp_text __pmu_switch_to_host(struct kvm_cpu_context *host_ctxt) write_sysreg(pmu->events_host, pmcntenset_el0); } +#define PMEVTYPER_READ_CASE(idx) \ + case idx: \ + return read_sysreg(pmevtyper##idx##_el0) + +#define PMEVTYPER_WRITE_CASE(idx) \ + case idx: \ + write_sysreg(val, pmevtyper##idx##_el0); \ + break + +#define PMEVTYPER_CASES(readwrite) \ + PMEVTYPER_##readwrite##_CASE(0); \ + PMEVTYPER_##readwrite##_CASE(1); \ + PMEVTYPER_##readwrite##_CASE(2); \ + PMEVTYPER_##readwrite##_CASE(3); \ + PMEVTYPER_##readwrite##_CASE(4); \ + PMEVTYPER_##readwrite##_CASE(5); \ + PMEVTYPER_##readwrite##_CASE(6); \ + PMEVTYPER_##readwrite##_CASE(7); \ + PMEVTYPER_##readwrite##_CASE(8); \ + PMEVTYPER_##readwrite##_CASE(9); \ + PMEVTYPER_##readwrite##_CASE(10); \ + PMEVTYPER_##readwrite##_CASE(11); \ + PMEVTYPER_##readwrite##_CASE(12); \ + PMEVTYPER_##readwrite##_CASE(13); \ + PMEVTYPER_##readwrite##_CASE(14); \ + PMEVTYPER_##readwrite##_CASE(15); \ + PMEVTYPER_##readwrite##_CASE(16); \ + PMEVTYPER_##readwrite##_CASE(17); \ + PMEVTYPER_##readwrite##_CASE(18); \ + PMEVTYPER_##readwrite##_CASE(19); \ + PMEVTYPER_##readwrite##_CASE(20); \ + PMEVTYPER_##readwrite##_CASE(21); \ + PMEVTYPER_##readwrite##_CASE(22); \ + PMEVTYPER_##readwrite##_CASE(23); \ + PMEVTYPER_##readwrite##_CASE(24); \ + PMEVTYPER_##readwrite##_CASE(25); \ + PMEVTYPER_##readwrite##_CASE(26); \ + PMEVTYPER_##readwrite##_CASE(27); \ + PMEVTYPER_##readwrite##_CASE(28); \ + PMEVTYPER_##readwrite##_CASE(29); \ + PMEVTYPER_##readwrite##_CASE(30) + +/* + * Read a value direct from PMEVTYPER + */ +static u64 kvm_vcpu_pmu_read_evtype_direct(int idx) +{ + switch (idx) { + PMEVTYPER_CASES(READ); + default: + WARN_ON(1); + } + + return 0; +} + +/* + * Write a value direct to PMEVTYPER + */ +static void kvm_vcpu_pmu_write_evtype_direct(int idx, u32 val) +{ + switch (idx) { + PMEVTYPER_CASES(WRITE); + default: + WARN_ON(1); + } +} + /* * Modify ARMv8 PMU events to include EL0 counting */ @@ -100,11 +168,9 @@ static void kvm_vcpu_pmu_enable_el0(unsigned long events) u32 counter; for_each_set_bit(counter, &events, 32) { - write_sysreg(counter, pmselr_el0); - isb(); - typer = read_sysreg(pmxevtyper_el0) & ~ARMV8_PMU_EXCLUDE_EL0; - write_sysreg(typer, pmxevtyper_el0); - isb(); + typer = kvm_vcpu_pmu_read_evtype_direct(counter); + typer &= ~ARMV8_PMU_EXCLUDE_EL0; + kvm_vcpu_pmu_write_evtype_direct(counter, typer); } } @@ -117,11 +183,9 @@ static void kvm_vcpu_pmu_disable_el0(unsigned long events) u32 counter; for_each_set_bit(counter, &events, 32) { - write_sysreg(counter, pmselr_el0); - isb(); - typer = read_sysreg(pmxevtyper_el0) | ARMV8_PMU_EXCLUDE_EL0; - write_sysreg(typer, pmxevtyper_el0); - isb(); + typer = kvm_vcpu_pmu_read_evtype_direct(counter); + typer |= ARMV8_PMU_EXCLUDE_EL0; + kvm_vcpu_pmu_write_evtype_direct(counter, typer); } }