From patchwork Tue Aug 27 15:25:08 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marc Zyngier X-Patchwork-Id: 13779695 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 1C2B01C7B97; Tue, 27 Aug 2024 15:25:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724772330; cv=none; b=sm1njVS79TBIHeo8xp0gkua0yWkWcFHhrBd0/wBQmOiymo+YZ3MTFcz50gaVKX/BGrNAVch/Sb38Nuq+YCtVDj/MdQAU6vURtUjHSUn5oc7IPiUQl78j/hq1x7n/vBAICUupDbFQKAuzyFb0T9Iiwxbd3JzKNZS6YyndAh5Of+8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724772330; c=relaxed/simple; bh=BLHqRlEtVdyFkvXOD5bpFwLzC1R/BZ+PStAiOyjpjRs=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=EcEkx70BcNXDgoRwgaofVdoYyFoZuqrS/2iLRcPKh2L+zOrmrMsIk7XUT+5OUkKJSIoMoisvJe3pnEkhF7FQ5y3l4UujRxrA6YoA77ug7jreEyEHrlu0z/FIrznKn7VfWxfZnMMohXU4Lv/GoARzy14QXM5Lx4s+M8Fx/upUAd4= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=MJuIGJIi; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="MJuIGJIi" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E3808C6107D; Tue, 27 Aug 2024 15:25:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1724772329; bh=BLHqRlEtVdyFkvXOD5bpFwLzC1R/BZ+PStAiOyjpjRs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=MJuIGJIia6/KJ2mCSm8jAmyCiuczqj4mBYPu6PAUnjQ4nLDQb0Xp+L1Nn6nWxk6oi 2liJsy07rmpM7sCAine/TvEywlYQZqyi4MNyP1MuGRlkAfGLLUx2qovBet+e+h1jv7 t7w7yN1uZPsSsLKqfzh5x8umvoV0MIG7uUHP1bKFQmob8dnaHU6J9tzGLJegIvuEOO HkdNqciW7QlsDT1faNog6E/0uE1qSu/ePnjynMvQIHpmPi48JyMemmLLslJxTtXPhL wYYY023zzM6BLsdVg0SGYvQQh1yyVbS9+DiUOrHikJLG6CdRgU8wJO8xQXoUl9G++0 Ta/4ictdRu82g== Received: from sofa.misterjones.org ([185.219.108.64] helo=valley-girl.lan) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.95) (envelope-from ) id 1siy4V-007HOs-Qc; Tue, 27 Aug 2024 16:25:27 +0100 From: Marc Zyngier To: kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, kvm@vger.kernel.org Cc: James Morse , Suzuki K Poulose , Oliver Upton , Zenghui Yu , Alexander Potapenko Subject: [PATCH v2 02/11] KVM: arm64: Force SRE traps when SRE access is not enabled Date: Tue, 27 Aug 2024 16:25:08 +0100 Message-Id: <20240827152517.3909653-3-maz@kernel.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20240827152517.3909653-1-maz@kernel.org> References: <20240827152517.3909653-1-maz@kernel.org> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, kvm@vger.kernel.org, james.morse@arm.com, suzuki.poulose@arm.com, oliver.upton@linux.dev, yuzenghui@huawei.com, glider@google.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false We so far only write the ICH_HCR_EL2 config in two situations: - when we need to emulate the GICv3 CPU interface due to HW bugs - when we do direct injection, as the virtual CPU interface needs to be enabled This is all good. But it also means that we don't do anything special when we emulate a GICv2, or that there is no GIC at all. What happens in this case when the guest uses the GICv3 system registers? The *guest* gets a trap for a sysreg access (EC=0x18) while we'd really like it to get an UNDEF. Fixing this is a bit involved: - we need to set all the required trap bits (TC, TALL0, TALL1, TDIR) - for these traps to take effect, we need to (counter-intuitively) set ICC_SRE_EL1.SRE to 1 so that the above traps take priority. Note that doesn't fully work when GICv2 emulation is enabled, as we cannot set ICC_SRE_EL1.SRE to 1 (it breaks Group0 delivery as IRQ). Signed-off-by: Marc Zyngier --- arch/arm64/kvm/hyp/vgic-v3-sr.c | 22 ++++++++++++++++------ arch/arm64/kvm/vgic/vgic-v3.c | 5 ++++- 2 files changed, 20 insertions(+), 7 deletions(-) diff --git a/arch/arm64/kvm/hyp/vgic-v3-sr.c b/arch/arm64/kvm/hyp/vgic-v3-sr.c index 7b397fad26f2..c9ab76652c32 100644 --- a/arch/arm64/kvm/hyp/vgic-v3-sr.c +++ b/arch/arm64/kvm/hyp/vgic-v3-sr.c @@ -268,8 +268,16 @@ void __vgic_v3_activate_traps(struct vgic_v3_cpu_if *cpu_if) * starting to mess with the rest of the GIC, and VMCR_EL2 in * particular. This logic must be called before * __vgic_v3_restore_state(). + * + * However, if the vgic is disabled (ICH_HCR_EL2.EN==0), no GIC is + * provisioned at all. In order to prevent illegal accesses to the + * system registers to trap to EL1 (duh), force ICC_SRE_EL1.SRE to 1 + * so that the trap bits can take effect. Yes, we *loves* the GIC. */ - if (!cpu_if->vgic_sre) { + if (!(cpu_if->vgic_hcr & ICH_HCR_EN)) { + write_gicreg(ICC_SRE_EL1_SRE, ICC_SRE_EL1); + isb(); + } else if (!cpu_if->vgic_sre) { write_gicreg(0, ICC_SRE_EL1); isb(); write_gicreg(cpu_if->vgic_vmcr, ICH_VMCR_EL2); @@ -288,8 +296,9 @@ void __vgic_v3_activate_traps(struct vgic_v3_cpu_if *cpu_if) } /* - * Prevent the guest from touching the GIC system registers if - * SRE isn't enabled for GICv3 emulation. + * Prevent the guest from touching the ICC_SRE_EL1 system + * register. Note that this may not have any effect, as + * ICC_SRE_EL2.Enable being RAO/WI is a valid implementation. */ write_gicreg(read_gicreg(ICC_SRE_EL2) & ~ICC_SRE_EL2_ENABLE, ICC_SRE_EL2); @@ -297,10 +306,11 @@ void __vgic_v3_activate_traps(struct vgic_v3_cpu_if *cpu_if) /* * If we need to trap system registers, we must write * ICH_HCR_EL2 anyway, even if no interrupts are being - * injected, + * injected. Note that this also applies if we don't expect + * any system register access (no vgic at all). */ if (static_branch_unlikely(&vgic_v3_cpuif_trap) || - cpu_if->its_vpe.its_vm) + cpu_if->its_vpe.its_vm || !cpu_if->vgic_sre) write_gicreg(cpu_if->vgic_hcr, ICH_HCR_EL2); } @@ -326,7 +336,7 @@ void __vgic_v3_deactivate_traps(struct vgic_v3_cpu_if *cpu_if) * no interrupts were being injected, and we disable it again here. */ if (static_branch_unlikely(&vgic_v3_cpuif_trap) || - cpu_if->its_vpe.its_vm) + cpu_if->its_vpe.its_vm || !cpu_if->vgic_sre) write_gicreg(0, ICH_HCR_EL2); } diff --git a/arch/arm64/kvm/vgic/vgic-v3.c b/arch/arm64/kvm/vgic/vgic-v3.c index 11718412921f..b217b256853c 100644 --- a/arch/arm64/kvm/vgic/vgic-v3.c +++ b/arch/arm64/kvm/vgic/vgic-v3.c @@ -298,8 +298,11 @@ void vcpu_set_ich_hcr(struct kvm_vcpu *vcpu) { struct vgic_v3_cpu_if *vgic_v3 = &vcpu->arch.vgic_cpu.vgic_v3; - if (!kvm_has_gicv3(vcpu->kvm)) + /* Hide GICv3 sysreg if necessary */ + if (!kvm_has_gicv3(vcpu->kvm)) { + vgic_v3->vgic_hcr |= ICH_HCR_TALL0 | ICH_HCR_TALL1 | ICH_HCR_TC; return; + } if (group0_trap) vgic_v3->vgic_hcr |= ICH_HCR_TALL0;