From mboxrd@z Thu Jan 1 00:00:00 1970 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id A51DCD6552C for ; Wed, 17 Dec 2025 10:13:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=w2+/nTtYL+8weY/4eCrE2hfZW1CFIFN9wNHzcGAsWS0=; b=2ex9RPcpcKW48ndWVNAdMS2nEn 1OzDNGIe96WN5ae3kzAwuRnzubeUTR68tYeI/DHU/JAkCvLBy5rmsHVVoYJc2gpeV7VnEurETzdZw 5ntsEHsNjoSf6bFx5YvSxoup4SrLGIYlFKPwK/Krykd/OajoeE7eFqTwu/vXycRN2P1Gsh/qaMcYU OKY56tuub82qFRj07Gx4g9F9WLO/dJzIDNEfjicpxIHSLi9PkmgjIQdNbto4WPRvJeBTk+LaY9QgR PB/ziFiytdzoI0K4IQ7J7mX6QnrnSlikwVPsnGWVm3XOpFdcO2MCjxNxSMHdKgpEzj25Mmh1P+rAL w1xcAjRA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vVoX7-00000006X94-0sVK; Wed, 17 Dec 2025 10:13:25 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vVoWx-00000006Wys-2D4E for linux-arm-kernel@lists.infradead.org; Wed, 17 Dec 2025 10:13:24 +0000 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 11E5A1688; Wed, 17 Dec 2025 02:13:07 -0800 (PST) Received: from e122027.arm.com (unknown [10.57.45.201]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id F32373F73B; Wed, 17 Dec 2025 02:13:09 -0800 (PST) From: Steven Price To: kvm@vger.kernel.org, kvmarm@lists.linux.dev Cc: Steven Price , Catalin Marinas , Marc Zyngier , Will Deacon , James Morse , Oliver Upton , Suzuki K Poulose , Zenghui Yu , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Joey Gouly , Alexandru Elisei , Christoffer Dall , Fuad Tabba , linux-coco@lists.linux.dev, Ganapatrao Kulkarni , Gavin Shan , Shanker Donthineni , Alper Gun , "Aneesh Kumar K . V" , Emi Kisanuki , Vishal Annapurve Subject: [PATCH v12 18/46] KVM: arm64: Handle realm MMIO emulation Date: Wed, 17 Dec 2025 10:10:55 +0000 Message-ID: <20251217101125.91098-19-steven.price@arm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20251217101125.91098-1-steven.price@arm.com> References: <20251217101125.91098-1-steven.price@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20251217_021315_700390_D375D2CC X-CRM114-Status: GOOD ( 19.55 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org MMIO emulation for a realm cannot be done directly with the VM's registers as they are protected from the host. However, for emulatable data aborts, the RMM uses GPRS[0] to provide the read/written value. We can transfer this from/to the equivalent VCPU's register entry and then depend on the generic MMIO handling code in KVM. For a MMIO read, the value is placed in the shared RecExit structure during kvm_handle_mmio_return() rather than in the VCPU's register entry. Signed-off-by: Steven Price Reviewed-by: Gavin Shan Reviewed-by: Suzuki K Poulose --- Changes since v7: * New comment for rec_exit_sync_dabt() explaining the call to vcpu_set_reg(). Changes since v5: * Inject SEA to the guest is an emulatable MMIO access triggers a data abort. * kvm_handle_mmio_return() - disable kvm_incr_pc() for a REC (as the PC isn't under the host's control) and move the REC_ENTER_EMULATED_MMIO flag setting to this location (as that tells the RMM to skip the instruction). --- arch/arm64/kvm/inject_fault.c | 4 +++- arch/arm64/kvm/mmio.c | 16 ++++++++++++---- arch/arm64/kvm/rmi-exit.c | 14 ++++++++++++++ 3 files changed, 29 insertions(+), 5 deletions(-) diff --git a/arch/arm64/kvm/inject_fault.c b/arch/arm64/kvm/inject_fault.c index dfcd66c65517..5e00f7a69bcc 100644 --- a/arch/arm64/kvm/inject_fault.c +++ b/arch/arm64/kvm/inject_fault.c @@ -224,7 +224,9 @@ static void inject_abt32(struct kvm_vcpu *vcpu, bool is_pabt, u32 addr) static void __kvm_inject_sea(struct kvm_vcpu *vcpu, bool iabt, u64 addr) { - if (vcpu_el1_is_32bit(vcpu)) + if (unlikely(vcpu_is_rec(vcpu))) + vcpu->arch.rec.run->enter.flags |= REC_ENTER_FLAG_INJECT_SEA; + else if (vcpu_el1_is_32bit(vcpu)) inject_abt32(vcpu, iabt, addr); else inject_abt64(vcpu, iabt, addr); diff --git a/arch/arm64/kvm/mmio.c b/arch/arm64/kvm/mmio.c index 54f9358c9e0e..d7ad291b5357 100644 --- a/arch/arm64/kvm/mmio.c +++ b/arch/arm64/kvm/mmio.c @@ -6,6 +6,7 @@ #include #include +#include #include #include "trace.h" @@ -138,14 +139,21 @@ int kvm_handle_mmio_return(struct kvm_vcpu *vcpu) trace_kvm_mmio(KVM_TRACE_MMIO_READ, len, run->mmio.phys_addr, &data); data = vcpu_data_host_to_guest(vcpu, data, len); - vcpu_set_reg(vcpu, kvm_vcpu_dabt_get_rd(vcpu), data); + + if (vcpu_is_rec(vcpu)) + vcpu->arch.rec.run->enter.gprs[0] = data; + else + vcpu_set_reg(vcpu, kvm_vcpu_dabt_get_rd(vcpu), data); } /* * The MMIO instruction is emulated and should not be re-executed * in the guest. */ - kvm_incr_pc(vcpu); + if (vcpu_is_rec(vcpu)) + vcpu->arch.rec.run->enter.flags |= REC_ENTER_FLAG_EMULATED_MMIO; + else + kvm_incr_pc(vcpu); return 1; } @@ -164,14 +172,14 @@ int io_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa) * No valid syndrome? Ask userspace for help if it has * volunteered to do so, and bail out otherwise. * - * In the protected VM case, there isn't much userspace can do + * In the protected/realm VM case, there isn't much userspace can do * though, so directly deliver an exception to the guest. */ if (!kvm_vcpu_dabt_isvalid(vcpu)) { trace_kvm_mmio_nisv(*vcpu_pc(vcpu), kvm_vcpu_get_esr(vcpu), kvm_vcpu_get_hfar(vcpu), fault_ipa); - if (vcpu_is_protected(vcpu)) + if (vcpu_is_protected(vcpu) || vcpu_is_rec(vcpu)) return kvm_inject_sea_dabt(vcpu, kvm_vcpu_get_hfar(vcpu)); if (test_bit(KVM_ARCH_FLAG_RETURN_NISV_IO_ABORT_TO_USER, diff --git a/arch/arm64/kvm/rmi-exit.c b/arch/arm64/kvm/rmi-exit.c index f5701153dec0..b4843f094615 100644 --- a/arch/arm64/kvm/rmi-exit.c +++ b/arch/arm64/kvm/rmi-exit.c @@ -25,6 +25,20 @@ static int rec_exit_reason_notimpl(struct kvm_vcpu *vcpu) static int rec_exit_sync_dabt(struct kvm_vcpu *vcpu) { + struct realm_rec *rec = &vcpu->arch.rec; + + /* + * In the case of a write, copy over gprs[0] to the target GPR, + * preparing to handle MMIO write fault. The content to be written has + * been saved to gprs[0] by the RMM (even if another register was used + * by the guest). In the case of normal memory access this is redundant + * (the guest will replay the instruction), but the overhead is + * minimal. + */ + if (kvm_vcpu_dabt_iswrite(vcpu) && kvm_vcpu_dabt_isvalid(vcpu)) + vcpu_set_reg(vcpu, kvm_vcpu_dabt_get_rd(vcpu), + rec->run->exit.gprs[0]); + return kvm_handle_guest_abort(vcpu); } -- 2.43.0