From nobody Thu Sep 11 16:49:41 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 2493DC001DB for ; Fri, 4 Aug 2023 10:14:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231393AbjHDKOg (ORCPT ); Fri, 4 Aug 2023 06:14:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59184 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231395AbjHDKN7 (ORCPT ); Fri, 4 Aug 2023 06:13:59 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 50B5446AC for ; Fri, 4 Aug 2023 03:13:52 -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 CA8D81007; Fri, 4 Aug 2023 03:14:34 -0700 (PDT) Received: from e127643.arm.com (unknown [10.57.3.154]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 4AC883F6C4; Fri, 4 Aug 2023 03:13:49 -0700 (PDT) From: James Clark To: coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev Cc: James Clark , Marc Zyngier , Oliver Upton , James Morse , Suzuki K Poulose , Zenghui Yu , Catalin Marinas , Will Deacon , Mike Leach , Leo Yan , Alexander Shishkin , Anshuman Khandual , Rob Herring , linux-kernel@vger.kernel.org Subject: [RFC PATCH 2/3] arm64: KVM: Support exclude_guest for Coresight trace in nVHE Date: Fri, 4 Aug 2023 11:13:12 +0100 Message-Id: <20230804101317.460697-3-james.clark@arm.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230804101317.460697-1-james.clark@arm.com> References: <20230804101317.460697-1-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" Currently trace will always be generated in nVHE as long as TRBE isn't being used. To allow filtering out guest trace, re-apply the filter rules before switching to the guest. The TRFCR restore function remains the same. Signed-off-by: James Clark --- arch/arm64/kvm/debug.c | 7 ++++ arch/arm64/kvm/hyp/nvhe/debug-sr.c | 56 +++++++++++++++++++++++++++--- 2 files changed, 59 insertions(+), 4 deletions(-) diff --git a/arch/arm64/kvm/debug.c b/arch/arm64/kvm/debug.c index 8725291cb00a..ebb4db20a859 100644 --- a/arch/arm64/kvm/debug.c +++ b/arch/arm64/kvm/debug.c @@ -335,10 +335,17 @@ void kvm_arch_vcpu_load_debug_state_flags(struct kvm_= vcpu *vcpu) 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_TRBE); + /* + * Save TRFCR on nVHE if FEAT_TRF exists. This will be done in cases + * where DEBUG_STATE_SAVE_TRBE doesn't completely disable trace. + */ + 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) { vcpu_clear_flag(vcpu, DEBUG_STATE_SAVE_SPE); vcpu_clear_flag(vcpu, DEBUG_STATE_SAVE_TRBE); + vcpu_clear_flag(vcpu, DEBUG_STATE_SAVE_TRFCR); } diff --git a/arch/arm64/kvm/hyp/nvhe/debug-sr.c b/arch/arm64/kvm/hyp/nvhe/d= ebug-sr.c index 4558c02eb352..0e8c85b29b92 100644 --- a/arch/arm64/kvm/hyp/nvhe/debug-sr.c +++ b/arch/arm64/kvm/hyp/nvhe/debug-sr.c @@ -51,13 +51,17 @@ static void __debug_restore_spe(u64 pmscr_el1) write_sysreg_s(pmscr_el1, SYS_PMSCR_EL1); } =20 -static void __debug_save_trace(u64 *trfcr_el1) +/* + * Save TRFCR and disable trace completely if TRBE is being used. Return t= rue + * if trace was disabled. + */ +static bool __debug_save_trace(u64 *trfcr_el1) { *trfcr_el1 =3D 0; =20 /* Check if the TRBE is enabled */ if (!(read_sysreg_s(SYS_TRBLIMITR_EL1) & TRBLIMITR_EL1_E)) - return; + return false; /* * Prohibit trace generation while we are in guest. * Since access to TRFCR_EL1 is trapped, the guest can't @@ -68,6 +72,8 @@ static void __debug_save_trace(u64 *trfcr_el1) isb(); /* Drain the trace buffer to memory */ tsb_csync(); + + return true; } =20 static void __debug_restore_trace(u64 trfcr_el1) @@ -79,14 +85,55 @@ static void __debug_restore_trace(u64 trfcr_el1) write_sysreg_s(trfcr_el1, SYS_TRFCR_EL1); } =20 +#if IS_ENABLED(CONFIG_PERF_EVENTS) +static inline void __debug_save_trfcr(struct kvm_vcpu *vcpu) +{ + u64 trfcr; + struct kvm_etm_event etm_event =3D vcpu->arch.host_debug_state.etm_event; + + /* No change if neither are excluded */ + if (!etm_event.exclude_guest && !etm_event.exclude_host) { + /* Zeroing prevents restoring a stale value */ + vcpu->arch.host_debug_state.trfcr_el1 =3D 0; + return; + } + + trfcr =3D read_sysreg_s(SYS_TRFCR_EL1); + vcpu->arch.host_debug_state.trfcr_el1 =3D trfcr; + + if (etm_event.exclude_guest) { + trfcr &=3D ~(TRFCR_ELx_ExTRE | TRFCR_ELx_E0TRE); + } else { + /* + * If host was excluded then EL0 and ELx tracing bits will + * already be cleared so they need to be set now for the guest. + */ + trfcr |=3D etm_event.exclude_kernel ? 0 : TRFCR_ELx_ExTRE; + trfcr |=3D etm_event.exclude_user ? 0 : TRFCR_ELx_E0TRE; + } + write_sysreg_s(trfcr, SYS_TRFCR_EL1); +} +#else +static inline void __debug_save_trfcr(struct kvm_vcpu *vcpu) {} +#endif + void __debug_save_host_buffers_nvhe(struct kvm_vcpu *vcpu) { + bool trc_disabled =3D false; + /* Disable and flush SPE data generation */ if (vcpu_get_flag(vcpu, DEBUG_STATE_SAVE_SPE)) __debug_save_spe(&vcpu->arch.host_debug_state.pmscr_el1); /* Disable and flush Self-Hosted Trace generation */ if (vcpu_get_flag(vcpu, DEBUG_STATE_SAVE_TRBE)) - __debug_save_trace(&vcpu->arch.host_debug_state.trfcr_el1); + trc_disabled =3D __debug_save_trace(&vcpu->arch.host_debug_state.trfcr_e= l1); + + /* + * As long as trace wasn't completely disabled due to use of TRBE, + * TRFCR can be saved and the exclude_guest rules applied. + */ + if (!trc_disabled && vcpu_get_flag(vcpu, DEBUG_STATE_SAVE_TRFCR)) + __debug_save_trfcr(vcpu); } =20 void __debug_switch_to_guest(struct kvm_vcpu *vcpu) @@ -98,7 +145,8 @@ void __debug_restore_host_buffers_nvhe(struct kvm_vcpu *= vcpu) { if (vcpu_get_flag(vcpu, DEBUG_STATE_SAVE_SPE)) __debug_restore_spe(vcpu->arch.host_debug_state.pmscr_el1); - if (vcpu_get_flag(vcpu, DEBUG_STATE_SAVE_TRBE)) + if (vcpu_get_flag(vcpu, DEBUG_STATE_SAVE_TRBE) || + vcpu_get_flag(vcpu, DEBUG_STATE_SAVE_TRFCR)) __debug_restore_trace(vcpu->arch.host_debug_state.trfcr_el1); } =20 --=20 2.34.1