From patchwork Mon May 15 17:30:20 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marc Zyngier X-Patchwork-Id: 13241957 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 3AAF0C77B7D for ; Mon, 15 May 2023 17:49:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244762AbjEORtz (ORCPT ); Mon, 15 May 2023 13:49:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46480 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244809AbjEORtV (ORCPT ); Mon, 15 May 2023 13:49:21 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2F05E1C38C for ; Mon, 15 May 2023 10:47:30 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id A3BF462EEB for ; Mon, 15 May 2023 17:47:30 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 160D0C433EF; Mon, 15 May 2023 17:47:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1684172850; bh=FXLDMwBfSiaxbM/iv7gBdscyJyoKDnWlDFKUyE1wYT8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=iBpJiMzRENDz6ozrv2nmVN0yFzZeKuUayCUAO+ZxPrx0YAq0VErQflTpeKItprFoY zeTeTqiGs0wJ7x2utPTDWHRv0hrIC7dEJsNG7aEh5f/vlf6SDvugk4oxeWprhccUIR rYncVWqDCzR0Q/nK2WazBIaLeE7q3WqFeNOGflP7lleyuBRciZTea+SqWaBR3hbhYX JoCUY0XYOxAxsVi2SWOfeXO5shW6C8o4a9L7orHv4x6rqUIQZ7UAOyEosRbSTV7PBO E+5apnncrpZbRclBidCmaHaCEgPxuyhOWtzhO6jQdP8iJCOITnvl2/7whHz6bVFhB+ TYm8DGZ7G6iiA== 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 1pyc2h-00FJAF-I1; Mon, 15 May 2023 18:31:27 +0100 From: Marc Zyngier To: kvmarm@lists.linux.dev, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org Cc: Alexandru Elisei , Andre Przywara , Chase Conklin , Christoffer Dall , Ganapatrao Kulkarni , Darren Hart , Jintack Lim , Russell King , Miguel Luis , James Morse , Suzuki K Poulose , Oliver Upton , Zenghui Yu Subject: [PATCH v10 16/59] KVM: arm64: nv: Handle SPSR_EL2 specially Date: Mon, 15 May 2023 18:30:20 +0100 Message-Id: <20230515173103.1017669-17-maz@kernel.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230515173103.1017669-1-maz@kernel.org> References: <20230515173103.1017669-1-maz@kernel.org> MIME-Version: 1.0 X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: kvmarm@lists.linux.dev, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, alexandru.elisei@arm.com, andre.przywara@arm.com, chase.conklin@arm.com, christoffer.dall@arm.com, gankulkarni@os.amperecomputing.com, darren@os.amperecomputing.com, jintack@cs.columbia.edu, rmk+kernel@armlinux.org.uk, miguel.luis@oracle.com, james.morse@arm.com, suzuki.poulose@arm.com, oliver.upton@linux.dev, yuzenghui@huawei.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org SPSR_EL2 needs special attention when running nested on ARMv8.3: If taking an exception while running at vEL2 (actually EL1), the HW will update the SPSR_EL1 register with the EL1 mode. We need to track this in order to make sure that accesses to the virtual view of SPSR_EL2 is correct. To do so, we place an illegal value in SPSR_EL1.M, and patch it accordingly if required when accessing it. Reviewed-by: Alexandru Elisei Reviewed-by: Russell King (Oracle) Signed-off-by: Marc Zyngier --- arch/arm64/include/asm/kvm_emulate.h | 37 ++++++++++++++++++++++++++++ arch/arm64/kvm/sys_regs.c | 23 +++++++++++++++-- 2 files changed, 58 insertions(+), 2 deletions(-) diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h index a08291051ac9..fd0979ba4328 100644 --- a/arch/arm64/include/asm/kvm_emulate.h +++ b/arch/arm64/include/asm/kvm_emulate.h @@ -251,6 +251,43 @@ static inline bool is_hyp_ctxt(const struct kvm_vcpu *vcpu) return __is_hyp_ctxt(&vcpu->arch.ctxt); } +static inline u64 __fixup_spsr_el2_write(struct kvm_cpu_context *ctxt, u64 val) +{ + if (!__vcpu_el2_e2h_is_set(ctxt)) { + /* + * Clear the .M field when writing SPSR to the CPU, so that we + * can detect when the CPU clobbered our SPSR copy during a + * local exception. + */ + val &= ~0xc; + } + + return val; +} + +static inline u64 __fixup_spsr_el2_read(const struct kvm_cpu_context *ctxt, u64 val) +{ + if (__vcpu_el2_e2h_is_set(ctxt)) + return val; + + /* + * SPSR.M == 0 means the CPU has not touched the SPSR, so the + * register has still the value we saved on the last write. + */ + if ((val & 0xc) == 0) + return ctxt_sys_reg(ctxt, SPSR_EL2); + + /* + * Otherwise there was a "local" exception on the CPU, + * which from the guest's point of view was being taken from + * EL2 to EL2, although it actually happened to be from + * EL1 to EL1. + * So we need to fix the .M field in SPSR, to make it look + * like EL2, which is what the guest would expect. + */ + return (val & ~0x0c) | CurrentEL_EL2; +} + /* * The layout of SPSR for an AArch32 state is different when observed from an * AArch64 SPSR_ELx or an AArch32 SPSR_*. This function generates the AArch32 diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c index 6e5783655b03..42397eae594e 100644 --- a/arch/arm64/kvm/sys_regs.c +++ b/arch/arm64/kvm/sys_regs.c @@ -130,11 +130,14 @@ u64 vcpu_read_sys_reg(const struct kvm_vcpu *vcpu, int reg) goto memory_read; /* - * ELR_EL2 is special cased for now. + * ELR_EL2 and SPSR_EL2 are special cased for now. */ switch (reg) { case ELR_EL2: return read_sysreg_el1(SYS_ELR); + case SPSR_EL2: + val = read_sysreg_el1(SYS_SPSR); + return __fixup_spsr_el2_read(&vcpu->arch.ctxt, val); } /* @@ -191,6 +194,10 @@ void vcpu_write_sys_reg(struct kvm_vcpu *vcpu, u64 val, int reg) case ELR_EL2: write_sysreg_el1(val, SYS_ELR); return; + case SPSR_EL2: + val = __fixup_spsr_el2_write(&vcpu->arch.ctxt, val); + write_sysreg_el1(val, SYS_SPSR); + return; } /* No EL1 counterpart? We're done here.? */ @@ -1876,6 +1883,18 @@ static bool access_spsr(struct kvm_vcpu *vcpu, return true; } +static bool access_spsr_el2(struct kvm_vcpu *vcpu, + struct sys_reg_params *p, + const struct sys_reg_desc *r) +{ + if (p->is_write) + vcpu_write_sys_reg(vcpu, p->regval, SPSR_EL2); + else + p->regval = vcpu_read_sys_reg(vcpu, SPSR_EL2); + + return true; +} + /* * Architected system registers. * Important: Must be sorted ascending by Op0, Op1, CRn, CRm, Op2 @@ -2324,7 +2343,7 @@ static const struct sys_reg_desc sys_reg_descs[] = { EL2_REG(VTCR_EL2, access_rw, reset_val, 0), { SYS_DESC(SYS_DACR32_EL2), NULL, reset_unknown, DACR32_EL2 }, - EL2_REG(SPSR_EL2, access_rw, reset_val, 0), + EL2_REG(SPSR_EL2, access_spsr_el2, reset_val, 0), EL2_REG(ELR_EL2, access_rw, reset_val, 0), { SYS_DESC(SYS_SP_EL1), access_sp_el1},