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 X-Spam-Level: X-Spam-Status: No, score=-21.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT, USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C9E45C636CA for ; Fri, 16 Jul 2021 21:26:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A9944613F3 for ; Fri, 16 Jul 2021 21:26:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235846AbhGPV3i (ORCPT ); Fri, 16 Jul 2021 17:29:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52714 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235173AbhGPV3h (ORCPT ); Fri, 16 Jul 2021 17:29:37 -0400 Received: from mail-yb1-xb49.google.com (mail-yb1-xb49.google.com [IPv6:2607:f8b0:4864:20::b49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 953ACC06175F for ; Fri, 16 Jul 2021 14:26:40 -0700 (PDT) Received: by mail-yb1-xb49.google.com with SMTP id x84-20020a2531570000b029055d47682463so14460816ybx.5 for ; Fri, 16 Jul 2021 14:26:40 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:message-id:mime-version:subject:from:to:cc; bh=CG1+N8vSAN8jzRMG92Z0vjc6XGG3WrzLze9UYb4OGFM=; b=hpALvyjB67nNiBWyNRqdwZIgq9/Ah4C1wy4WzyAhOF1YMY/PbIl+5JKuOIwVYnwWXL yHkH+Q76WdRKmp3DXfrvnGBgf3RmSHMMJP1rsysV+s0a0bDxSckfFBsAmpPs5qMieJPr Z/4fTJy3iUAL++yl1gG/rPWRtSIQlPEv0nTGfhj0vmNoICTnPyCUDw85Scu6xFnhxqQ/ PCl5syulBaA+CBZq01RP/dqRWltjhNxXD34Gf3fbM6nhoBWFHS0MzyhH4DCJ8wLeMicH vzXbhsT3y3DycKc2TTueJe29yKr7LdDQxOI22pnAgKXyUZZrFRHTKRIqBL2NhrtrEbTw SYhQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:message-id:mime-version:subject:from:to:cc; bh=CG1+N8vSAN8jzRMG92Z0vjc6XGG3WrzLze9UYb4OGFM=; b=PagxCMssjpTFrF++4XViuzQiK0gh7B78acx4oL9kFeNOnqdfxTrcUPnvoMuRwxj4zx dAN13SGroKETrpJOUcsuEwPAOlfoxzdFZYnNFoYXMuu+Hr7lGssbNc9mI6FkFKvUXC2T uo5YicQBgpociuwlZ6wmXi3pTxHPlQmXlSZ8UF8/N1XcDdlEcK5SdbWPXCxrziiN6Ims e9LA5KJRnC4oYKCW+3o3NPWkqkux5b/j0We/mesM/kzEW3iB9253oLKPYECyfBLC46i0 sxuR/Do69Xsg1oN4U9oL29H8+/QjRWtL7+Hx7o4zuQ7DT0vgLH9AbB4tM1+oo17ljDC5 oJig== X-Gm-Message-State: AOAM531bJqTzL1ilvu6iFqzfYLBLdkI0UjwPypx5ZR4gKLe7U1zhXfUs g88g2oGF3tLY2U9JAZZ80V9Q4lBJCmnYZ0Di5PlZJBz663eCWhbAFmzwwAUn1BxN+KjFRcKJYMI qj0J4lP2It3O3dIABUdskff80WEp8JvuCg6mJXvWHPNdYe0qy8XVYLY4ULg== X-Google-Smtp-Source: ABdhPJyM4yakm1D1JS9PB+woXsIw2d1EI19Wm7mHRgWc5nFPgvVvTY/SC4vCot6IQ4tGKqy+FEet80OPohc= X-Received: from oupton.c.googlers.com ([fda3:e722:ac3:cc00:2b:ff92:c0a8:404]) (user=oupton job=sendgmr) by 2002:a25:ed0b:: with SMTP id k11mr14179470ybh.39.1626470799678; Fri, 16 Jul 2021 14:26:39 -0700 (PDT) Date: Fri, 16 Jul 2021 21:26:17 +0000 Message-Id: <20210716212629.2232756-1-oupton@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.32.0.402.g57bb445576-goog Subject: [PATCH v2 00/12] KVM: Add idempotent controls for migrating system counter state From: Oliver Upton To: kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu Cc: Paolo Bonzini , Sean Christopherson , Marc Zyngier , Peter Shier , Jim Mattson , David Matlack , Ricardo Koller , Jing Zhang , Raghavendra Rao Anata , James Morse , Alexandru Elisei , Suzuki K Poulose , linux-arm-kernel@lists.infradead.org, Oliver Upton Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org KVM's current means of saving/restoring system counters is plagued with temporal issues. At least on ARM64 and x86, we migrate the guest's system counter by-value through the respective guest system register values (cntvct_el0, ia32_tsc). Restoring system counters by-value is brittle as the state is not idempotent: the host system counter is still oscillating between the attempted save and restore. Furthermore, VMMs may wish to transparently live migrate guest VMs, meaning that they include the elapsed time due to live migration blackout in the guest system counter view. The VMM thread could be preempted for any number of reasons (scheduler, L0 hypervisor under nested) between the time that it calculates the desired guest counter value and when KVM actually sets this counter state. Despite the value-based interface that we present to userspace, KVM actually has idempotent guest controls by way of system counter offsets. We can avoid all of the issues associated with a value-based interface by abstracting these offset controls in new ioctls. This series introduces new vCPU device attributes to provide userspace access to the vCPU's system counter offset. Patch 1 adopts Paolo's suggestion, augmenting the KVM_{GET,SET}_CLOCK ioctls to provide userspace with a (host_tsc, realtime) instant. This is essential for a VMM to perform precise migration of the guest's system counters. Patches 2-3 add support for x86 by shoehorning the new controls into the pre-existing synchronization heuristics. Patches 4-5 implement a test for the new additions to KVM_{GET,SET}_CLOCK. Patches 6-7 implement at test for the tsc offset attribute introduced in patch 3. Patch 8 adds a device attribute for the arm64 virtual counter-timer offset. Patch 9 extends the test from patch 7 to cover the arm64 virtual counter-timer offset. Patch 10 adds a device attribute for the arm64 physical counter-timer offset. Currently, this is implemented as a synthetic register, forcing the guest to trap to the host and emulating the offset in the fast exit path. Later down the line we will have hardware with FEAT_ECV, which allows the hypervisor to perform physical counter-timer offsetting in hardware (CNTPOFF_EL2). Patch 11 extends the test from patch 7 to cover the arm64 physical counter-timer offset. Patch 12 introduces a benchmark to measure the overhead of emulation in patch 10. Physical counter benchmark -------------------------- The following data was collected by running 10000 iterations of the benchmark test from Patch 6 on an Ampere Mt. Jade reference server, A 2S machine with 2 80-core Ampere Altra SoCs. Measurements were collected for both VHE and nVHE operation using the `kvm-arm.mode=` command-line parameter. nVHE ---- +--------------------+--------+---------+ | Metric | Native | Trapped | +--------------------+--------+---------+ | Average | 54ns | 148ns | | Standard Deviation | 124ns | 122ns | | 95th Percentile | 258ns | 348ns | +--------------------+--------+---------+ VHE --- +--------------------+--------+---------+ | Metric | Native | Trapped | +--------------------+--------+---------+ | Average | 53ns | 152ns | | Standard Deviation | 92ns | 94ns | | 95th Percentile | 204ns | 307ns | +--------------------+--------+---------+ This series applies cleanly to the following commit: 1889228d80fe ("KVM: selftests: smm_test: Test SMM enter from L2") v1 -> v2: - Reimplemented as vCPU device attributes instead of a distinct ioctl. - Added the (realtime, host_tsc) instant support to KVM_{GET,SET}_CLOCK - Changed the arm64 implementation to broadcast counter offset values to all vCPUs in a guest. This upholds the architectural expectations of a consistent counter-timer across CPUs. - Fixed a bug with traps in VHE mode. We now configure traps on every transition into a guest to handle differing VMs (trapped, emulated). Oliver Upton (12): KVM: x86: Report host tsc and realtime values in KVM_GET_CLOCK KVM: x86: Refactor tsc synchronization code KVM: x86: Expose TSC offset controls to userspace tools: arch: x86: pull in pvclock headers selftests: KVM: Add test for KVM_{GET,SET}_CLOCK selftests: KVM: Add helpers for vCPU device attributes selftests: KVM: Introduce system counter offset test KVM: arm64: Allow userspace to configure a vCPU's virtual offset selftests: KVM: Add support for aarch64 to system_counter_offset_test KVM: arm64: Provide userspace access to the physical counter offset selftests: KVM: Test physical counter offsetting selftests: KVM: Add counter emulation benchmark Documentation/virt/kvm/api.rst | 42 +- Documentation/virt/kvm/locking.rst | 11 + arch/arm64/include/asm/kvm_host.h | 1 + arch/arm64/include/asm/kvm_hyp.h | 2 - arch/arm64/include/asm/sysreg.h | 1 + arch/arm64/include/uapi/asm/kvm.h | 2 + arch/arm64/kvm/arch_timer.c | 118 ++++- arch/arm64/kvm/arm.c | 4 +- arch/arm64/kvm/hyp/include/hyp/switch.h | 23 + arch/arm64/kvm/hyp/include/hyp/timer-sr.h | 26 ++ arch/arm64/kvm/hyp/nvhe/switch.c | 2 - arch/arm64/kvm/hyp/nvhe/timer-sr.c | 21 +- arch/arm64/kvm/hyp/vhe/timer-sr.c | 27 ++ arch/x86/include/asm/kvm_host.h | 4 + arch/x86/include/uapi/asm/kvm.h | 4 + arch/x86/kvm/x86.c | 421 ++++++++++++++---- include/kvm/arm_arch_timer.h | 2 - include/uapi/linux/kvm.h | 7 +- tools/arch/x86/include/asm/pvclock-abi.h | 48 ++ tools/arch/x86/include/asm/pvclock.h | 103 +++++ tools/testing/selftests/kvm/.gitignore | 3 + tools/testing/selftests/kvm/Makefile | 4 + .../kvm/aarch64/counter_emulation_benchmark.c | 215 +++++++++ .../selftests/kvm/include/aarch64/processor.h | 24 + .../testing/selftests/kvm/include/kvm_util.h | 11 + tools/testing/selftests/kvm/lib/kvm_util.c | 38 ++ .../kvm/system_counter_offset_test.c | 206 +++++++++ .../selftests/kvm/x86_64/kvm_clock_test.c | 210 +++++++++ 28 files changed, 1447 insertions(+), 133 deletions(-) create mode 100644 arch/arm64/kvm/hyp/include/hyp/timer-sr.h create mode 100644 tools/arch/x86/include/asm/pvclock-abi.h create mode 100644 tools/arch/x86/include/asm/pvclock.h create mode 100644 tools/testing/selftests/kvm/aarch64/counter_emulation_benchmark.c create mode 100644 tools/testing/selftests/kvm/system_counter_offset_test.c create mode 100644 tools/testing/selftests/kvm/x86_64/kvm_clock_test.c -- 2.32.0.402.g57bb445576-goog 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 X-Spam-Level: X-Spam-Status: No, score=-11.5 required=3.0 tests=BAYES_00, DKIM_ADSP_CUSTOM_MED,DKIM_INVALID,DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A6492C636CD for ; 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charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu KVM's current means of saving/restoring system counters is plagued with temporal issues. At least on ARM64 and x86, we migrate the guest's system counter by-value through the respective guest system register values (cntvct_el0, ia32_tsc). Restoring system counters by-value is brittle as the state is not idempotent: the host system counter is still oscillating between the attempted save and restore. Furthermore, VMMs may wish to transparently live migrate guest VMs, meaning that they include the elapsed time due to live migration blackout in the guest system counter view. The VMM thread could be preempted for any number of reasons (scheduler, L0 hypervisor under nested) between the time that it calculates the desired guest counter value and when KVM actually sets this counter state. Despite the value-based interface that we present to userspace, KVM actually has idempotent guest controls by way of system counter offsets. We can avoid all of the issues associated with a value-based interface by abstracting these offset controls in new ioctls. This series introduces new vCPU device attributes to provide userspace access to the vCPU's system counter offset. Patch 1 adopts Paolo's suggestion, augmenting the KVM_{GET,SET}_CLOCK ioctls to provide userspace with a (host_tsc, realtime) instant. This is essential for a VMM to perform precise migration of the guest's system counters. Patches 2-3 add support for x86 by shoehorning the new controls into the pre-existing synchronization heuristics. Patches 4-5 implement a test for the new additions to KVM_{GET,SET}_CLOCK. Patches 6-7 implement at test for the tsc offset attribute introduced in patch 3. Patch 8 adds a device attribute for the arm64 virtual counter-timer offset. Patch 9 extends the test from patch 7 to cover the arm64 virtual counter-timer offset. Patch 10 adds a device attribute for the arm64 physical counter-timer offset. Currently, this is implemented as a synthetic register, forcing the guest to trap to the host and emulating the offset in the fast exit path. Later down the line we will have hardware with FEAT_ECV, which allows the hypervisor to perform physical counter-timer offsetting in hardware (CNTPOFF_EL2). Patch 11 extends the test from patch 7 to cover the arm64 physical counter-timer offset. Patch 12 introduces a benchmark to measure the overhead of emulation in patch 10. Physical counter benchmark -------------------------- The following data was collected by running 10000 iterations of the benchmark test from Patch 6 on an Ampere Mt. Jade reference server, A 2S machine with 2 80-core Ampere Altra SoCs. Measurements were collected for both VHE and nVHE operation using the `kvm-arm.mode=` command-line parameter. nVHE ---- +--------------------+--------+---------+ | Metric | Native | Trapped | +--------------------+--------+---------+ | Average | 54ns | 148ns | | Standard Deviation | 124ns | 122ns | | 95th Percentile | 258ns | 348ns | +--------------------+--------+---------+ VHE --- +--------------------+--------+---------+ | Metric | Native | Trapped | +--------------------+--------+---------+ | Average | 53ns | 152ns | | Standard Deviation | 92ns | 94ns | | 95th Percentile | 204ns | 307ns | +--------------------+--------+---------+ This series applies cleanly to the following commit: 1889228d80fe ("KVM: selftests: smm_test: Test SMM enter from L2") v1 -> v2: - Reimplemented as vCPU device attributes instead of a distinct ioctl. - Added the (realtime, host_tsc) instant support to KVM_{GET,SET}_CLOCK - Changed the arm64 implementation to broadcast counter offset values to all vCPUs in a guest. This upholds the architectural expectations of a consistent counter-timer across CPUs. - Fixed a bug with traps in VHE mode. We now configure traps on every transition into a guest to handle differing VMs (trapped, emulated). Oliver Upton (12): KVM: x86: Report host tsc and realtime values in KVM_GET_CLOCK KVM: x86: Refactor tsc synchronization code KVM: x86: Expose TSC offset controls to userspace tools: arch: x86: pull in pvclock headers selftests: KVM: Add test for KVM_{GET,SET}_CLOCK selftests: KVM: Add helpers for vCPU device attributes selftests: KVM: Introduce system counter offset test KVM: arm64: Allow userspace to configure a vCPU's virtual offset selftests: KVM: Add support for aarch64 to system_counter_offset_test KVM: arm64: Provide userspace access to the physical counter offset selftests: KVM: Test physical counter offsetting selftests: KVM: Add counter emulation benchmark Documentation/virt/kvm/api.rst | 42 +- Documentation/virt/kvm/locking.rst | 11 + arch/arm64/include/asm/kvm_host.h | 1 + arch/arm64/include/asm/kvm_hyp.h | 2 - arch/arm64/include/asm/sysreg.h | 1 + arch/arm64/include/uapi/asm/kvm.h | 2 + arch/arm64/kvm/arch_timer.c | 118 ++++- arch/arm64/kvm/arm.c | 4 +- arch/arm64/kvm/hyp/include/hyp/switch.h | 23 + arch/arm64/kvm/hyp/include/hyp/timer-sr.h | 26 ++ arch/arm64/kvm/hyp/nvhe/switch.c | 2 - arch/arm64/kvm/hyp/nvhe/timer-sr.c | 21 +- arch/arm64/kvm/hyp/vhe/timer-sr.c | 27 ++ arch/x86/include/asm/kvm_host.h | 4 + arch/x86/include/uapi/asm/kvm.h | 4 + arch/x86/kvm/x86.c | 421 ++++++++++++++---- include/kvm/arm_arch_timer.h | 2 - include/uapi/linux/kvm.h | 7 +- tools/arch/x86/include/asm/pvclock-abi.h | 48 ++ tools/arch/x86/include/asm/pvclock.h | 103 +++++ tools/testing/selftests/kvm/.gitignore | 3 + tools/testing/selftests/kvm/Makefile | 4 + .../kvm/aarch64/counter_emulation_benchmark.c | 215 +++++++++ .../selftests/kvm/include/aarch64/processor.h | 24 + .../testing/selftests/kvm/include/kvm_util.h | 11 + tools/testing/selftests/kvm/lib/kvm_util.c | 38 ++ .../kvm/system_counter_offset_test.c | 206 +++++++++ .../selftests/kvm/x86_64/kvm_clock_test.c | 210 +++++++++ 28 files changed, 1447 insertions(+), 133 deletions(-) create mode 100644 arch/arm64/kvm/hyp/include/hyp/timer-sr.h create mode 100644 tools/arch/x86/include/asm/pvclock-abi.h create mode 100644 tools/arch/x86/include/asm/pvclock.h create mode 100644 tools/testing/selftests/kvm/aarch64/counter_emulation_benchmark.c create mode 100644 tools/testing/selftests/kvm/system_counter_offset_test.c create mode 100644 tools/testing/selftests/kvm/x86_64/kvm_clock_test.c -- 2.32.0.402.g57bb445576-goog _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm 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 X-Spam-Level: X-Spam-Status: No, score=-12.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_ADSP_CUSTOM_MED,DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5CC2CC12002 for ; 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Fri, 16 Jul 2021 14:26:39 -0700 (PDT) Date: Fri, 16 Jul 2021 21:26:17 +0000 Message-Id: <20210716212629.2232756-1-oupton@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.32.0.402.g57bb445576-goog Subject: [PATCH v2 00/12] KVM: Add idempotent controls for migrating system counter state From: Oliver Upton To: kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu Cc: Paolo Bonzini , Sean Christopherson , Marc Zyngier , Peter Shier , Jim Mattson , David Matlack , Ricardo Koller , Jing Zhang , Raghavendra Rao Anata , James Morse , Alexandru Elisei , Suzuki K Poulose , linux-arm-kernel@lists.infradead.org, Oliver Upton X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210716_142642_123183_5A2ED7FA X-CRM114-Status: GOOD ( 20.22 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org KVM's current means of saving/restoring system counters is plagued with temporal issues. At least on ARM64 and x86, we migrate the guest's system counter by-value through the respective guest system register values (cntvct_el0, ia32_tsc). Restoring system counters by-value is brittle as the state is not idempotent: the host system counter is still oscillating between the attempted save and restore. Furthermore, VMMs may wish to transparently live migrate guest VMs, meaning that they include the elapsed time due to live migration blackout in the guest system counter view. The VMM thread could be preempted for any number of reasons (scheduler, L0 hypervisor under nested) between the time that it calculates the desired guest counter value and when KVM actually sets this counter state. Despite the value-based interface that we present to userspace, KVM actually has idempotent guest controls by way of system counter offsets. We can avoid all of the issues associated with a value-based interface by abstracting these offset controls in new ioctls. This series introduces new vCPU device attributes to provide userspace access to the vCPU's system counter offset. Patch 1 adopts Paolo's suggestion, augmenting the KVM_{GET,SET}_CLOCK ioctls to provide userspace with a (host_tsc, realtime) instant. This is essential for a VMM to perform precise migration of the guest's system counters. Patches 2-3 add support for x86 by shoehorning the new controls into the pre-existing synchronization heuristics. Patches 4-5 implement a test for the new additions to KVM_{GET,SET}_CLOCK. Patches 6-7 implement at test for the tsc offset attribute introduced in patch 3. Patch 8 adds a device attribute for the arm64 virtual counter-timer offset. Patch 9 extends the test from patch 7 to cover the arm64 virtual counter-timer offset. Patch 10 adds a device attribute for the arm64 physical counter-timer offset. Currently, this is implemented as a synthetic register, forcing the guest to trap to the host and emulating the offset in the fast exit path. Later down the line we will have hardware with FEAT_ECV, which allows the hypervisor to perform physical counter-timer offsetting in hardware (CNTPOFF_EL2). Patch 11 extends the test from patch 7 to cover the arm64 physical counter-timer offset. Patch 12 introduces a benchmark to measure the overhead of emulation in patch 10. Physical counter benchmark -------------------------- The following data was collected by running 10000 iterations of the benchmark test from Patch 6 on an Ampere Mt. Jade reference server, A 2S machine with 2 80-core Ampere Altra SoCs. Measurements were collected for both VHE and nVHE operation using the `kvm-arm.mode=` command-line parameter. nVHE ---- +--------------------+--------+---------+ | Metric | Native | Trapped | +--------------------+--------+---------+ | Average | 54ns | 148ns | | Standard Deviation | 124ns | 122ns | | 95th Percentile | 258ns | 348ns | +--------------------+--------+---------+ VHE --- +--------------------+--------+---------+ | Metric | Native | Trapped | +--------------------+--------+---------+ | Average | 53ns | 152ns | | Standard Deviation | 92ns | 94ns | | 95th Percentile | 204ns | 307ns | +--------------------+--------+---------+ This series applies cleanly to the following commit: 1889228d80fe ("KVM: selftests: smm_test: Test SMM enter from L2") v1 -> v2: - Reimplemented as vCPU device attributes instead of a distinct ioctl. - Added the (realtime, host_tsc) instant support to KVM_{GET,SET}_CLOCK - Changed the arm64 implementation to broadcast counter offset values to all vCPUs in a guest. This upholds the architectural expectations of a consistent counter-timer across CPUs. - Fixed a bug with traps in VHE mode. We now configure traps on every transition into a guest to handle differing VMs (trapped, emulated). Oliver Upton (12): KVM: x86: Report host tsc and realtime values in KVM_GET_CLOCK KVM: x86: Refactor tsc synchronization code KVM: x86: Expose TSC offset controls to userspace tools: arch: x86: pull in pvclock headers selftests: KVM: Add test for KVM_{GET,SET}_CLOCK selftests: KVM: Add helpers for vCPU device attributes selftests: KVM: Introduce system counter offset test KVM: arm64: Allow userspace to configure a vCPU's virtual offset selftests: KVM: Add support for aarch64 to system_counter_offset_test KVM: arm64: Provide userspace access to the physical counter offset selftests: KVM: Test physical counter offsetting selftests: KVM: Add counter emulation benchmark Documentation/virt/kvm/api.rst | 42 +- Documentation/virt/kvm/locking.rst | 11 + arch/arm64/include/asm/kvm_host.h | 1 + arch/arm64/include/asm/kvm_hyp.h | 2 - arch/arm64/include/asm/sysreg.h | 1 + arch/arm64/include/uapi/asm/kvm.h | 2 + arch/arm64/kvm/arch_timer.c | 118 ++++- arch/arm64/kvm/arm.c | 4 +- arch/arm64/kvm/hyp/include/hyp/switch.h | 23 + arch/arm64/kvm/hyp/include/hyp/timer-sr.h | 26 ++ arch/arm64/kvm/hyp/nvhe/switch.c | 2 - arch/arm64/kvm/hyp/nvhe/timer-sr.c | 21 +- arch/arm64/kvm/hyp/vhe/timer-sr.c | 27 ++ arch/x86/include/asm/kvm_host.h | 4 + arch/x86/include/uapi/asm/kvm.h | 4 + arch/x86/kvm/x86.c | 421 ++++++++++++++---- include/kvm/arm_arch_timer.h | 2 - include/uapi/linux/kvm.h | 7 +- tools/arch/x86/include/asm/pvclock-abi.h | 48 ++ tools/arch/x86/include/asm/pvclock.h | 103 +++++ tools/testing/selftests/kvm/.gitignore | 3 + tools/testing/selftests/kvm/Makefile | 4 + .../kvm/aarch64/counter_emulation_benchmark.c | 215 +++++++++ .../selftests/kvm/include/aarch64/processor.h | 24 + .../testing/selftests/kvm/include/kvm_util.h | 11 + tools/testing/selftests/kvm/lib/kvm_util.c | 38 ++ .../kvm/system_counter_offset_test.c | 206 +++++++++ .../selftests/kvm/x86_64/kvm_clock_test.c | 210 +++++++++ 28 files changed, 1447 insertions(+), 133 deletions(-) create mode 100644 arch/arm64/kvm/hyp/include/hyp/timer-sr.h create mode 100644 tools/arch/x86/include/asm/pvclock-abi.h create mode 100644 tools/arch/x86/include/asm/pvclock.h create mode 100644 tools/testing/selftests/kvm/aarch64/counter_emulation_benchmark.c create mode 100644 tools/testing/selftests/kvm/system_counter_offset_test.c create mode 100644 tools/testing/selftests/kvm/x86_64/kvm_clock_test.c -- 2.32.0.402.g57bb445576-goog _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel