From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 338845FEE9 for ; Mon, 26 Feb 2024 10:15:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708942505; cv=none; b=e4oSTtWTvxEcP+zKZc8h+iKeIe+BjvMBO6Crf3ngPyUcKpJAaLD+1GIPtdBwP/vzj9KOzRxQlkXZU+XqqBdaFHWmfu+7pViioB7k42Y6jixcYX6KOa9Vyg/OaimGykXengxGfyGB6Bb6wp4+j2RR22CUNS86QNUVRsMVeeplhyE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708942505; c=relaxed/simple; bh=6GQ4h/oDGendPMzWfxwIWWvA/xDItW3TKyAauSavtv8=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=TKpn4j35r551D2cUNs7M3lssn5saBPZYSR6pE97hksf9+tK+gZYDmkM5UkjmVpSRQphpxheIoO3CeeQFVeS9n06R3vRd4aqDxXp6pqHE65Z+zTvr4jvcjxtAOQ7PzgYDDLlitVNhnPaNd0W5okhPg3t0pZOe238gDHBUN6cPVpA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com 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 4E695DA7; Mon, 26 Feb 2024 02:15:41 -0800 (PST) Received: from [10.57.50.187] (unknown [10.57.50.187]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 7A5613F6C4; Mon, 26 Feb 2024 02:14:58 -0800 (PST) Message-ID: <1d2a6c09-6892-48fc-a7fb-e171c7fbd814@arm.com> Date: Mon, 26 Feb 2024 10:14:56 +0000 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 6/7] arm64: KVM: Write TRFCR value on guest switch with nVHE Content-Language: en-GB To: James Clark , coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, maz@kernel.org, acme@kernel.org, oliver.upton@linux.dev, broonie@kernel.org Cc: James Morse , Zenghui Yu , Catalin Marinas , Will Deacon , Mike Leach , Alexander Shishkin , Anshuman Khandual , Miguel Luis , Joey Gouly , Ard Biesheuvel , Arnd Bergmann , Helge Deller , Greg Kroah-Hartman , Mark Rutland , Kalesh Singh , Ryan Roberts , Vincent Donnefort , Fuad Tabba , Jing Zhang , linux-kernel@vger.kernel.org References: <20240220100924.2761706-1-james.clark@arm.com> <20240220100924.2761706-7-james.clark@arm.com> From: Suzuki K Poulose In-Reply-To: <20240220100924.2761706-7-james.clark@arm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 20/02/2024 10:09, James Clark wrote: > The guest value for TRFCR requested by the Coresight driver is saved in > kvm_guest_trfcr. 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. > > In pKVM, the kvm_guest_trfcr can't be read and the host isn't trusted, > so always disable trace. > > __debug_restore_trace() now has to restore unconditionally, because even > a value of 0 needs to be written to overwrite whatever was set for the > guest. > > Signed-off-by: James Clark Reviewed-by: Suzuki K Poulose > --- > arch/arm64/kvm/hyp/nvhe/debug-sr.c | 53 +++++++++++++++++------------- > 1 file changed, 31 insertions(+), 22 deletions(-) > > diff --git a/arch/arm64/kvm/hyp/nvhe/debug-sr.c b/arch/arm64/kvm/hyp/nvhe/debug-sr.c > index 4558c02eb352..3adac2e01908 100644 > --- a/arch/arm64/kvm/hyp/nvhe/debug-sr.c > +++ b/arch/arm64/kvm/hyp/nvhe/debug-sr.c > @@ -51,30 +51,39 @@ static void __debug_restore_spe(u64 pmscr_el1) > write_sysreg_s(pmscr_el1, SYS_PMSCR_EL1); > } > > -static void __debug_save_trace(u64 *trfcr_el1) > +static void __debug_save_trace(struct kvm_vcpu *vcpu) > { > - *trfcr_el1 = 0; > - > - /* 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. > - */ > - *trfcr_el1 = read_sysreg_s(SYS_TRFCR_EL1); > - write_sysreg_s(0, SYS_TRFCR_EL1); > - isb(); > - /* Drain the trace buffer to memory */ > - tsb_csync(); > + u64 host_trfcr_el1 = read_sysreg_s(SYS_TRFCR_EL1); > + u64 guest_trfcr_el1; > + > + vcpu->arch.host_debug_state.trfcr_el1 = host_trfcr_el1; > + > + /* Check if the TRBE buffer or pKVM is enabled */ > + if (is_protected_kvm_enabled() || > + (vcpu_get_flag(vcpu, DEBUG_STATE_SAVE_TRBE) && > + 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. > + */ > + write_sysreg_s(0, SYS_TRFCR_EL1); > + isb(); > + /* Drain the trace buffer to memory */ > + tsb_csync(); > + } else { > + /* > + * Tracing is allowed, apply the filters provided by the > + * Coresight driver. > + */ > + guest_trfcr_el1 = kvm_guest_trfcr[vcpu->cpu]; > + if (host_trfcr_el1 != guest_trfcr_el1) > + write_sysreg_s(guest_trfcr_el1, SYS_TRFCR_EL1); > + } > } > > static void __debug_restore_trace(u64 trfcr_el1) > { > - if (!trfcr_el1) > - return; > - > /* Restore trace filter controls */ > write_sysreg_s(trfcr_el1, SYS_TRFCR_EL1); > } > @@ -85,8 +94,8 @@ void __debug_save_host_buffers_nvhe(struct kvm_vcpu *vcpu) > 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); > + if (vcpu_get_flag(vcpu, DEBUG_STATE_SAVE_TRFCR)) > + __debug_save_trace(vcpu); > } > > void __debug_switch_to_guest(struct kvm_vcpu *vcpu) > @@ -98,7 +107,7 @@ 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_TRFCR)) > __debug_restore_trace(vcpu->arch.host_debug_state.trfcr_el1); > } >