From nobody Thu Dec 18 06:03:59 2025 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E50B0E92702 for ; Thu, 5 Oct 2023 14:37:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236818AbjJEOhF (ORCPT ); Thu, 5 Oct 2023 10:37:05 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46436 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236270AbjJEOeo (ORCPT ); Thu, 5 Oct 2023 10:34:44 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 82FA259DA for ; Thu, 5 Oct 2023 06:53:19 -0700 (PDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 77F9F1691; Thu, 5 Oct 2023 05:59:35 -0700 (PDT) Received: from localhost.localdomain (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id CB5A83F641; Thu, 5 Oct 2023 05:58:53 -0700 (PDT) From: James Clark To: coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, broonie@kernel.org, maz@kernel.org, suzuki.poulose@arm.com Cc: James Clark , Oliver Upton , James Morse , Zenghui Yu , Catalin Marinas , Will Deacon , Mike Leach , Leo Yan , Alexander Shishkin , Anshuman Khandual , Rob Herring , Jintack Lim , Akihiko Odaki , Fuad Tabba , Joey Gouly , linux-kernel@vger.kernel.org Subject: [PATCH v2 5/6] arm64: KVM: Write TRFCR value on guest switch with nVHE Date: Thu, 5 Oct 2023 13:57:53 +0100 Message-Id: <20231005125757.649345-6-james.clark@arm.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20231005125757.649345-1-james.clark@arm.com> References: <20231005125757.649345-1-james.clark@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" The guest value for TRFCR requested by the Coresight driver is saved in sysregs[TRFCR_EL1]. On guest switch this value needs to be written to the register. Currently TRFCR is only modified when we want to disable trace completely in guests due to an issue with TRBE. Expand the __debug_save_trace() function to always write to the register if a different value for guests is required, but also keep the existing TRBE disable behavior if that's required. The TRFCR restore function remains functionally the same, except a value of 0 doesn't mean "don't restore" anymore. Now that we save both guest and host values the register is restored any time the guest and host values differ. Signed-off-by: James Clark --- arch/arm64/include/asm/kvm_hyp.h | 6 ++- arch/arm64/kvm/debug.c | 13 +++++- arch/arm64/kvm/hyp/nvhe/debug-sr.c | 63 ++++++++++++++++++------------ arch/arm64/kvm/hyp/nvhe/switch.c | 4 +- 4 files changed, 57 insertions(+), 29 deletions(-) diff --git a/arch/arm64/include/asm/kvm_hyp.h b/arch/arm64/include/asm/kvm_= hyp.h index 37e238f526d7..0383fd3d60b5 100644 --- a/arch/arm64/include/asm/kvm_hyp.h +++ b/arch/arm64/include/asm/kvm_hyp.h @@ -103,8 +103,10 @@ void __debug_switch_to_guest(struct kvm_vcpu *vcpu); void __debug_switch_to_host(struct kvm_vcpu *vcpu); =20 #ifdef __KVM_NVHE_HYPERVISOR__ -void __debug_save_host_buffers_nvhe(struct kvm_cpu_context *host_ctxt); -void __debug_restore_host_buffers_nvhe(struct kvm_cpu_context *host_ctxt); +void __debug_save_host_buffers_nvhe(struct kvm_cpu_context *host_ctxt, + struct kvm_cpu_context *guest_ctxt); +void __debug_restore_host_buffers_nvhe(struct kvm_cpu_context *host_ctxt, + struct kvm_cpu_context *guest_ctxt); #endif =20 void __fpsimd_save_state(struct user_fpsimd_state *fp_regs); diff --git a/arch/arm64/kvm/debug.c b/arch/arm64/kvm/debug.c index 19e722359154..d949dd354464 100644 --- a/arch/arm64/kvm/debug.c +++ b/arch/arm64/kvm/debug.c @@ -337,10 +337,21 @@ void kvm_arch_vcpu_load_debug_state_flags(struct kvm_= vcpu *vcpu) !(read_sysreg_s(SYS_PMBIDR_EL1) & BIT(PMBIDR_EL1_P_SHIFT))) vcpu_set_flag(vcpu, DEBUG_STATE_SAVE_SPE); =20 - /* Check if we have TRBE implemented and available at the host */ + /* + * Check if we have TRBE implemented and available at the host. If it's + * in use at the time of guest switch it will need to be disabled and + * then restored. + */ if (cpuid_feature_extract_unsigned_field(dfr0, ID_AA64DFR0_EL1_TraceBuffe= r_SHIFT) && !(read_sysreg_s(SYS_TRBIDR_EL1) & TRBIDR_EL1_P)) vcpu_set_flag(vcpu, DEBUG_STATE_SAVE_TRFCR); + /* + * Also save TRFCR on nVHE if FEAT_TRF (TraceFilt) exists. This will be + * done in cases where use of TRBE doesn't completely disable trace and + * handles the exclude_host/exclude_guest rules of the trace session. + */ + if (cpuid_feature_extract_unsigned_field(dfr0, ID_AA64DFR0_EL1_TraceFilt_= SHIFT)) + vcpu_set_flag(vcpu, DEBUG_STATE_SAVE_TRFCR); } =20 void kvm_arch_vcpu_put_debug_state_flags(struct kvm_vcpu *vcpu) diff --git a/arch/arm64/kvm/hyp/nvhe/debug-sr.c b/arch/arm64/kvm/hyp/nvhe/d= ebug-sr.c index 128a57dddabf..c6252029c277 100644 --- a/arch/arm64/kvm/hyp/nvhe/debug-sr.c +++ b/arch/arm64/kvm/hyp/nvhe/debug-sr.c @@ -51,42 +51,56 @@ static void __debug_restore_spe(struct kvm_cpu_context = *host_ctxt) write_sysreg_s(ctxt_sys_reg(host_ctxt, PMSCR_EL1), SYS_PMSCR_EL1); } =20 -static void __debug_save_trace(struct kvm_cpu_context *host_ctxt) +/* + * Save TRFCR and disable trace completely if TRBE is being used, otherwise + * apply required guest TRFCR value. + */ +static void __debug_save_trace(struct kvm_cpu_context *host_ctxt, + struct kvm_cpu_context *guest_ctxt) { - ctxt_sys_reg(host_ctxt, TRFCR_EL1) =3D 0; + ctxt_sys_reg(host_ctxt, TRFCR_EL1) =3D read_sysreg_s(SYS_TRFCR_EL1); =20 /* Check if the TRBE is enabled */ - if (!(read_sysreg_s(SYS_TRBLIMITR_EL1) & TRBLIMITR_EL1_E)) - return; - /* - * Prohibit trace generation while we are in guest. - * Since access to TRFCR_EL1 is trapped, the guest can't - * modify the filtering set by the host. - */ - ctxt_sys_reg(host_ctxt, TRFCR_EL1) =3D read_sysreg_s(SYS_TRFCR_EL1); - write_sysreg_s(0, SYS_TRFCR_EL1); - isb(); - /* Drain the trace buffer to memory */ - tsb_csync(); + if (read_sysreg_s(SYS_TRBLIMITR_EL1) & TRBLIMITR_EL1_E) { + /* + * Prohibit trace generation while we are in guest. Since access + * to TRFCR_EL1 is trapped, the guest can't modify the filtering + * set by the host. + */ + ctxt_sys_reg(guest_ctxt, TRFCR_EL1) =3D 0; + write_sysreg_s(0, SYS_TRFCR_EL1); + isb(); + /* Drain the trace buffer to memory */ + tsb_csync(); + } else { + /* + * Not using TRBE, so guest trace works. Apply the guest filters + * provided by the Coresight driver, if different. + */ + if (ctxt_sys_reg(host_ctxt, TRFCR_EL1) !=3D + ctxt_sys_reg(guest_ctxt, TRFCR_EL1)) + write_sysreg_s(ctxt_sys_reg(guest_ctxt, TRFCR_EL1), + SYS_TRFCR_EL1); + } } =20 -static void __debug_restore_trace(struct kvm_cpu_context *host_ctxt) +static void __debug_restore_trace(struct kvm_cpu_context *host_ctxt, + struct kvm_cpu_context *guest_ctxt) { - if (!ctxt_sys_reg(host_ctxt, TRFCR_EL1)) - return; - /* Restore trace filter controls */ - write_sysreg_s(ctxt_sys_reg(host_ctxt, TRFCR_EL1), SYS_TRFCR_EL1); + if (ctxt_sys_reg(host_ctxt, TRFCR_EL1) !=3D ctxt_sys_reg(guest_ctxt, TRFC= R_EL1)) + write_sysreg_s(ctxt_sys_reg(host_ctxt, TRFCR_EL1), SYS_TRFCR_EL1); } =20 -void __debug_save_host_buffers_nvhe(struct kvm_cpu_context *host_ctxt) +void __debug_save_host_buffers_nvhe(struct kvm_cpu_context *host_ctxt, + struct kvm_cpu_context *guest_ctxt) { /* Disable and flush SPE data generation */ if (vcpu_get_flag(host_ctxt->__hyp_running_vcpu, DEBUG_STATE_SAVE_SPE)) __debug_save_spe(host_ctxt); - /* Disable and flush Self-Hosted Trace generation */ + if (vcpu_get_flag(host_ctxt->__hyp_running_vcpu, DEBUG_STATE_SAVE_TRFCR)) - __debug_save_trace(host_ctxt); + __debug_save_trace(host_ctxt, guest_ctxt); } =20 void __debug_switch_to_guest(struct kvm_vcpu *vcpu) @@ -94,12 +108,13 @@ void __debug_switch_to_guest(struct kvm_vcpu *vcpu) __debug_switch_to_guest_common(vcpu); } =20 -void __debug_restore_host_buffers_nvhe(struct kvm_cpu_context *host_ctxt) +void __debug_restore_host_buffers_nvhe(struct kvm_cpu_context *host_ctxt, + struct kvm_cpu_context *guest_ctxt) { if (vcpu_get_flag(host_ctxt->__hyp_running_vcpu, DEBUG_STATE_SAVE_SPE)) __debug_restore_spe(host_ctxt); if (vcpu_get_flag(host_ctxt->__hyp_running_vcpu, DEBUG_STATE_SAVE_TRFCR)) - __debug_restore_trace(host_ctxt); + __debug_restore_trace(host_ctxt, guest_ctxt); } =20 void __debug_switch_to_host(struct kvm_vcpu *vcpu) diff --git a/arch/arm64/kvm/hyp/nvhe/switch.c b/arch/arm64/kvm/hyp/nvhe/swi= tch.c index c8f15e4dab19..55207ec31bd3 100644 --- a/arch/arm64/kvm/hyp/nvhe/switch.c +++ b/arch/arm64/kvm/hyp/nvhe/switch.c @@ -276,7 +276,7 @@ int __kvm_vcpu_run(struct kvm_vcpu *vcpu) * translation regime to EL2 (via MDCR_EL2_E2PB =3D=3D 0) and * before we load guest Stage1. */ - __debug_save_host_buffers_nvhe(host_ctxt); + __debug_save_host_buffers_nvhe(host_ctxt, guest_ctxt); =20 /* * We're about to restore some new MMU state. Make sure @@ -343,7 +343,7 @@ int __kvm_vcpu_run(struct kvm_vcpu *vcpu) * This must come after restoring the host sysregs, since a non-VHE * system may enable SPE here and make use of the TTBRs. */ - __debug_restore_host_buffers_nvhe(host_ctxt); + __debug_restore_host_buffers_nvhe(host_ctxt, guest_ctxt); =20 if (pmu_switch_needed) __pmu_switch_to_host(vcpu); --=20 2.34.1