From patchwork Thu Jun 13 20:17:52 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Oliver Upton X-Patchwork-Id: 13697437 Received: from out-182.mta1.migadu.com (out-182.mta1.migadu.com [95.215.58.182]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2F7A913BAD9 for ; Thu, 13 Jun 2024 20:18:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.182 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718309933; cv=none; b=u/EsX9L8KXE8ys1DhKl1EtFDZXaLOpdJpi/S5MRbJwinp+tEygQLua31uGEf2FGj/LRA788/SgHc9ks8XRpTyE+v/u/pVI0B8Tiy9oHuwJHBaelf+YT+DzhfPcoUkj97o83xB+ahbHCjcSk/AiWR+CEAbJQ3h4v+xMS5kssVEKw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718309933; c=relaxed/simple; bh=1gQ3VJDYhI3w4SWiYVcsOD8IwGrYRiv41a2jO6SUv14=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=pvZaclmWnpw1I3PphXplnUcWICKByH2Bq1ByZa94naiMS/1Z0PWVhaAbXnJeCsA/y3/V0BlEJ1qKpQKRKCFsEjacVLTNbjQsShosV5nKLf3l0LXXCY2AJ5GvY/eTyR3z+nf6h6KGeKAtRZEB00D68U+r0w8jaxJvdfcmQRaRuQQ= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=CINM/8cW; arc=none smtp.client-ip=95.215.58.182 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="CINM/8cW" X-Envelope-To: kvmarm@lists.linux.dev DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1718309930; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=mgvqC7WLJslUQDWVjGnfKGGRyKxketT5brA13gOHVto=; b=CINM/8cWnYHxX8TDH255lzbUrTIAdQIaZGK0pZq2tYDXKPdPgs2wYgBspeEyZWNDURBEBG Dj9FoqitEUn7igmDyljujKs0OxPgYRUlMdg8yM2GxPDgC7c3CxJ1lbAX3+TikI4B9Lk1it XKfb1PfudV1vfnV5fGJSzlVUnqrr3tw= X-Envelope-To: maz@kernel.org X-Envelope-To: james.morse@arm.com X-Envelope-To: suzuki.poulose@arm.com X-Envelope-To: yuzenghui@huawei.com X-Envelope-To: kvm@vger.kernel.org X-Envelope-To: tabba@google.com X-Envelope-To: oliver.upton@linux.dev X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Oliver Upton To: kvmarm@lists.linux.dev Cc: Marc Zyngier , James Morse , Suzuki K Poulose , Zenghui Yu , kvm@vger.kernel.org, Fuad Tabba , Oliver Upton Subject: [PATCH v2 11/15] KVM: arm64: nv: Honor guest hypervisor's FP/SVE traps in CPTR_EL2 Date: Thu, 13 Jun 2024 20:17:52 +0000 Message-ID: <20240613201756.3258227-12-oliver.upton@linux.dev> In-Reply-To: <20240613201756.3258227-1-oliver.upton@linux.dev> References: <20240613201756.3258227-1-oliver.upton@linux.dev> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Migadu-Flow: FLOW_OUT Start folding the guest hypervisor's FP/SVE traps into the value programmed in hardware. Note that as of writing this is dead code, since KVM does a full put() / load() for every nested exception boundary which saves + flushes the FP/SVE state. However, this will become useful when we can keep the guest's FP/SVE state alive across a nested exception boundary and the host no longer needs to conservatively program traps. Signed-off-by: Oliver Upton --- arch/arm64/kvm/hyp/vhe/switch.c | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+) diff --git a/arch/arm64/kvm/hyp/vhe/switch.c b/arch/arm64/kvm/hyp/vhe/switch.c index 925de4b4efd2..b0b1935a3626 100644 --- a/arch/arm64/kvm/hyp/vhe/switch.c +++ b/arch/arm64/kvm/hyp/vhe/switch.c @@ -67,6 +67,8 @@ static u64 __compute_hcr(struct kvm_vcpu *vcpu) static void __activate_cptr_traps(struct kvm_vcpu *vcpu) { + u64 cptr; + /* * With VHE (HCR.E2H == 1), accesses to CPACR_EL1 are routed to * CPTR_EL2. In general, CPACR_EL1 has the same layout as CPTR_EL2, @@ -85,6 +87,35 @@ static void __activate_cptr_traps(struct kvm_vcpu *vcpu) __activate_traps_fpsimd32(vcpu); } + /* + * Layer the guest hypervisor's trap configuration on top of our own if + * we're in a nested context. + */ + if (!vcpu_has_nv(vcpu) || is_hyp_ctxt(vcpu)) + goto write; + + cptr = vcpu_sanitised_cptr_el2(vcpu); + + /* + * Pay attention, there's some interesting detail here. + * + * The CPTR_EL2.xEN fields are 2 bits wide, although there are only two + * meaningful trap states when HCR_EL2.TGE = 0 (running a nested guest): + * + * - CPTR_EL2.xEN = x0, traps are enabled + * - CPTR_EL2.xEN = x1, traps are disabled + * + * In other words, bit[0] determines if guest accesses trap or not. In + * the interest of simplicity, clear the entire field if the guest + * hypervisor has traps enabled to dispel any illusion of something more + * complicated taking place. + */ + if (!(SYS_FIELD_GET(CPACR_ELx, FPEN, cptr) & BIT(0))) + val &= ~CPACR_ELx_FPEN; + if (!(SYS_FIELD_GET(CPACR_ELx, ZEN, cptr) & BIT(0))) + val &= ~CPACR_ELx_ZEN; + +write: write_sysreg(val, cpacr_el1); }