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 76668C35FFC for ; Tue, 25 Mar 2025 11:34:06 +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: Content-Type:MIME-Version:Message-ID:In-Reply-To:Date:From:Cc:To:Subject: Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender :Resent-To:Resent-Cc:Resent-Message-ID:References:List-Owner; bh=3PzHoiiYWwuODrGgSRfkIXsgPySoD6CmPnD64Lz2XoU=; b=mJo4mk5QiqPxhQwNojHhQfNckw /f9sjXb8dvP9H81wW+4iF+sX7PJjxgOHZK39oS5POw5E3wB+Ll+kcB/1whxHpgy06kOZoOJQRiwwW YDA2tftYpvX63yHGYto5Bat1TTVQyuXkoX7+6UADDyH1X1cahNjp/gZxhz3BpfQTp4cZYdWT7m6Yc E5S/EL+8TD7lUxJbiQdIERpQ+X40R5G8FU/TZ/Rf0ttPJtbIOkXlZSJSo3Ni9wxl43yc9jJMoMOH5 gro4UV74odlvpbrJANf9CydSL98skdcUHHmd/sjJQ+Q9+GkXKLojiXZ9NjWa7z4GH+Pjk6lHNk9+j aHQT08Gg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.1 #2 (Red Hat Linux)) id 1tx2XX-00000005e3v-3WbM; Tue, 25 Mar 2025 11:33:51 +0000 Received: from sea.source.kernel.org ([172.234.252.31]) by bombadil.infradead.org with esmtps (Exim 4.98.1 #2 (Red Hat Linux)) id 1tx2UF-00000005dhw-02sQ for linux-arm-kernel@lists.infradead.org; Tue, 25 Mar 2025 11:30:28 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 692EE43BC0; Tue, 25 Mar 2025 11:30:26 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5FFD4C4CEE4; Tue, 25 Mar 2025 11:30:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1742902226; bh=vx7g4XThZtP1UK+IOSayBzfIGr3eLuhEHg0cjzVtu7A=; h=Subject:To:Cc:From:Date:In-Reply-To:From; b=bFgZ0Luz6mxq39fVLAiuFjrl5amRCHzTWl5aMWkSDvu5wtanx/1AD5AGf2oblEaiU vaubNrHMc2KFz2+b6Ykn+YzxsHqm23flApupce4pDrviSf5/96ZxxBWtm69k7HXUUg z3N4lqG0FBp774ZlLSjjq5e/GhROc3CHGtZKq4xE= Subject: Patch "KVM: arm64: Eagerly switch ZCR_EL{1,2}" has been added to the 6.6-stable tree To: broonie@kernel.org,catalin.marinas@arm.com,gregkh@linuxfoundation.org,james.morse@arm.com,kvmarm@lists.linux.dev,linux-arm-kernel@lists.infradead.org,mark.rutland@arm.com,maz@kernel.org,oliver.upton@linux.dev,suzuki.poulose@arm.com,tabba@google.com,will@kernel.org Cc: From: Date: Tue, 25 Mar 2025 07:28:55 -0400 In-Reply-To: <20250321-stable-sve-6-6-v1-8-0b3a6a14ea53@kernel.org> Message-ID: <2025032555-wimp-try-c46c@gregkh> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit X-stable: commit X-Patchwork-Hint: ignore X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250325_043027_102434_073B4B5E X-CRM114-Status: GOOD ( 35.84 ) 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 This is a note to let you know that I've just added the patch titled KVM: arm64: Eagerly switch ZCR_EL{1,2} to the 6.6-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: kvm-arm64-eagerly-switch-zcr_el-1-2.patch and it can be found in the queue-6.6 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >From broonie@kernel.org Thu Mar 20 20:18:40 2025 From: Mark Brown Date: Fri, 21 Mar 2025 00:16:08 +0000 Subject: KVM: arm64: Eagerly switch ZCR_EL{1,2} To: Greg Kroah-Hartman , Marc Zyngier , Oliver Upton , James Morse , Suzuki K Poulose , Catalin Marinas , Will Deacon Cc: linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Mark Brown , Mark Rutland , Fuad Tabba Message-ID: <20250321-stable-sve-6-6-v1-8-0b3a6a14ea53@kernel.org> From: Mark Rutland [ Upstream commit 59419f10045bc955d2229819c7cf7a8b0b9c5b59 ] In non-protected KVM modes, while the guest FPSIMD/SVE/SME state is live on the CPU, the host's active SVE VL may differ from the guest's maximum SVE VL: * For VHE hosts, when a VM uses NV, ZCR_EL2 contains a value constrained by the guest hypervisor, which may be less than or equal to that guest's maximum VL. Note: in this case the value of ZCR_EL1 is immaterial due to E2H. * For nVHE/hVHE hosts, ZCR_EL1 contains a value written by the guest, which may be less than or greater than the guest's maximum VL. Note: in this case hyp code traps host SVE usage and lazily restores ZCR_EL2 to the host's maximum VL, which may be greater than the guest's maximum VL. This can be the case between exiting a guest and kvm_arch_vcpu_put_fp(). If a softirq is taken during this period and the softirq handler tries to use kernel-mode NEON, then the kernel will fail to save the guest's FPSIMD/SVE state, and will pend a SIGKILL for the current thread. This happens because kvm_arch_vcpu_ctxsync_fp() binds the guest's live FPSIMD/SVE state with the guest's maximum SVE VL, and fpsimd_save_user_state() verifies that the live SVE VL is as expected before attempting to save the register state: | if (WARN_ON(sve_get_vl() != vl)) { | force_signal_inject(SIGKILL, SI_KERNEL, 0, 0); | return; | } Fix this and make this a bit easier to reason about by always eagerly switching ZCR_EL{1,2} at hyp during guest<->host transitions. With this happening, there's no need to trap host SVE usage, and the nVHE/nVHE __deactivate_cptr_traps() logic can be simplified to enable host access to all present FPSIMD/SVE/SME features. In protected nVHE/hVHE modes, the host's state is always saved/restored by hyp, and the guest's state is saved prior to exit to the host, so from the host's PoV the guest never has live FPSIMD/SVE/SME state, and the host's ZCR_EL1 is never clobbered by hyp. Fixes: 8c8010d69c132273 ("KVM: arm64: Save/restore SVE state for nVHE") Fixes: 2e3cf82063a00ea0 ("KVM: arm64: nv: Ensure correct VL is loaded before saving SVE state") Signed-off-by: Mark Rutland Reviewed-by: Mark Brown Tested-by: Mark Brown Cc: Catalin Marinas Cc: Fuad Tabba Cc: Marc Zyngier Cc: Oliver Upton Cc: Will Deacon Reviewed-by: Oliver Upton Link: https://lore.kernel.org/r/20250210195226.1215254-9-mark.rutland@arm.com Signed-off-by: Marc Zyngier [ v6.6 lacks pKVM saving of host SVE state, pull in discovery of maximum host VL separately -- broonie ] Signed-off-by: Mark Brown Signed-off-by: Greg Kroah-Hartman --- arch/arm64/include/asm/kvm_host.h | 1 arch/arm64/include/asm/kvm_hyp.h | 1 arch/arm64/kvm/fpsimd.c | 19 +++++------ arch/arm64/kvm/hyp/entry.S | 5 ++ arch/arm64/kvm/hyp/include/hyp/switch.h | 55 ++++++++++++++++++++++++++++++++ arch/arm64/kvm/hyp/nvhe/hyp-main.c | 12 +----- arch/arm64/kvm/hyp/nvhe/pkvm.c | 2 + arch/arm64/kvm/hyp/nvhe/switch.c | 33 ++++++++++++++++--- arch/arm64/kvm/hyp/vhe/switch.c | 4 ++ arch/arm64/kvm/reset.c | 3 + 10 files changed, 113 insertions(+), 22 deletions(-) --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -73,6 +73,7 @@ static inline enum kvm_mode kvm_get_mode #endif extern unsigned int __ro_after_init kvm_sve_max_vl; +extern unsigned int __ro_after_init kvm_host_sve_max_vl; int __init kvm_arm_init_sve(void); u32 __attribute_const__ kvm_target_cpu(void); --- a/arch/arm64/include/asm/kvm_hyp.h +++ b/arch/arm64/include/asm/kvm_hyp.h @@ -145,5 +145,6 @@ extern u64 kvm_nvhe_sym(id_aa64smfr0_el1 extern unsigned long kvm_nvhe_sym(__icache_flags); extern unsigned int kvm_nvhe_sym(kvm_arm_vmid_bits); +extern unsigned int kvm_nvhe_sym(kvm_host_sve_max_vl); #endif /* __ARM64_KVM_HYP_H__ */ --- a/arch/arm64/kvm/fpsimd.c +++ b/arch/arm64/kvm/fpsimd.c @@ -152,15 +152,16 @@ void kvm_arch_vcpu_put_fp(struct kvm_vcp local_irq_save(flags); if (vcpu->arch.fp_state == FP_STATE_GUEST_OWNED) { - if (vcpu_has_sve(vcpu)) { - __vcpu_sys_reg(vcpu, ZCR_EL1) = read_sysreg_el1(SYS_ZCR); - - /* Restore the VL that was saved when bound to the CPU */ - if (!has_vhe()) - sve_cond_update_zcr_vq(vcpu_sve_max_vq(vcpu) - 1, - SYS_ZCR_EL1); - } - + /* + * Flush (save and invalidate) the fpsimd/sve state so that if + * the host tries to use fpsimd/sve, it's not using stale data + * from the guest. + * + * Flushing the state sets the TIF_FOREIGN_FPSTATE bit for the + * context unconditionally, in both nVHE and VHE. This allows + * the kernel to restore the fpsimd/sve state, including ZCR_EL1 + * when needed. + */ fpsimd_save_and_flush_cpu_state(); } --- a/arch/arm64/kvm/hyp/entry.S +++ b/arch/arm64/kvm/hyp/entry.S @@ -44,6 +44,11 @@ alternative_if ARM64_HAS_RAS_EXTN alternative_else_nop_endif mrs x1, isr_el1 cbz x1, 1f + + // Ensure that __guest_enter() always provides a context + // synchronization event so that callers don't need ISBs for anything + // that would usually be synchonized by the ERET. + isb mov x0, #ARM_EXCEPTION_IRQ ret --- a/arch/arm64/kvm/hyp/include/hyp/switch.h +++ b/arch/arm64/kvm/hyp/include/hyp/switch.h @@ -273,6 +273,61 @@ static inline void __hyp_sve_restore_gue write_sysreg_el1(__vcpu_sys_reg(vcpu, ZCR_EL1), SYS_ZCR); } +static inline void fpsimd_lazy_switch_to_guest(struct kvm_vcpu *vcpu) +{ + u64 zcr_el1, zcr_el2; + + if (!guest_owns_fp_regs(vcpu)) + return; + + if (vcpu_has_sve(vcpu)) { + zcr_el2 = vcpu_sve_max_vq(vcpu) - 1; + + write_sysreg_el2(zcr_el2, SYS_ZCR); + + zcr_el1 = __vcpu_sys_reg(vcpu, ZCR_EL1); + write_sysreg_el1(zcr_el1, SYS_ZCR); + } +} + +static inline void fpsimd_lazy_switch_to_host(struct kvm_vcpu *vcpu) +{ + u64 zcr_el1, zcr_el2; + + if (!guest_owns_fp_regs(vcpu)) + return; + + /* + * When the guest owns the FP regs, we know that guest+hyp traps for + * any FPSIMD/SVE/SME features exposed to the guest have been disabled + * by either fpsimd_lazy_switch_to_guest() or kvm_hyp_handle_fpsimd() + * prior to __guest_entry(). As __guest_entry() guarantees a context + * synchronization event, we don't need an ISB here to avoid taking + * traps for anything that was exposed to the guest. + */ + if (vcpu_has_sve(vcpu)) { + zcr_el1 = read_sysreg_el1(SYS_ZCR); + __vcpu_sys_reg(vcpu, ZCR_EL1) = zcr_el1; + + /* + * The guest's state is always saved using the guest's max VL. + * Ensure that the host has the guest's max VL active such that + * the host can save the guest's state lazily, but don't + * artificially restrict the host to the guest's max VL. + */ + if (has_vhe()) { + zcr_el2 = vcpu_sve_max_vq(vcpu) - 1; + write_sysreg_el2(zcr_el2, SYS_ZCR); + } else { + zcr_el2 = sve_vq_from_vl(kvm_host_sve_max_vl) - 1; + write_sysreg_el2(zcr_el2, SYS_ZCR); + + zcr_el1 = vcpu_sve_max_vq(vcpu) - 1; + write_sysreg_el1(zcr_el1, SYS_ZCR); + } + } +} + /* * We trap the first access to the FP/SIMD to save the host context and * restore the guest context lazily. --- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c +++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c @@ -5,6 +5,7 @@ */ #include +#include #include #include @@ -95,7 +96,9 @@ static void handle___kvm_vcpu_run(struct pkvm_put_hyp_vcpu(hyp_vcpu); } else { /* The host is fully trusted, run its vCPU directly. */ + fpsimd_lazy_switch_to_guest(host_vcpu); ret = __kvm_vcpu_run(host_vcpu); + fpsimd_lazy_switch_to_host(host_vcpu); } out: @@ -416,15 +419,6 @@ void handle_trap(struct kvm_cpu_context case ESR_ELx_EC_SMC64: handle_host_smc(host_ctxt); break; - case ESR_ELx_EC_SVE: - if (has_hvhe()) - sysreg_clear_set(cpacr_el1, 0, (CPACR_EL1_ZEN_EL1EN | - CPACR_EL1_ZEN_EL0EN)); - else - sysreg_clear_set(cptr_el2, CPTR_EL2_TZ, 0); - isb(); - sve_cond_update_zcr_vq(ZCR_ELx_LEN_MASK, SYS_ZCR_EL2); - break; case ESR_ELx_EC_IABT_LOW: case ESR_ELx_EC_DABT_LOW: handle_host_mem_abort(host_ctxt); --- a/arch/arm64/kvm/hyp/nvhe/pkvm.c +++ b/arch/arm64/kvm/hyp/nvhe/pkvm.c @@ -18,6 +18,8 @@ unsigned long __icache_flags; /* Used by kvm_get_vttbr(). */ unsigned int kvm_arm_vmid_bits; +unsigned int kvm_host_sve_max_vl; + /* * Set trap register values based on features in ID_AA64PFR0. */ --- a/arch/arm64/kvm/hyp/nvhe/switch.c +++ b/arch/arm64/kvm/hyp/nvhe/switch.c @@ -40,6 +40,9 @@ static void __activate_cptr_traps(struct { u64 val = CPTR_EL2_TAM; /* Same bit irrespective of E2H */ + if (!guest_owns_fp_regs(vcpu)) + __activate_traps_fpsimd32(vcpu); + if (has_hvhe()) { val |= CPACR_ELx_TTA; @@ -48,6 +51,8 @@ static void __activate_cptr_traps(struct if (vcpu_has_sve(vcpu)) val |= CPACR_ELx_ZEN; } + + write_sysreg(val, cpacr_el1); } else { val |= CPTR_EL2_TTA | CPTR_NVHE_EL2_RES1; @@ -62,12 +67,32 @@ static void __activate_cptr_traps(struct if (!guest_owns_fp_regs(vcpu)) val |= CPTR_EL2_TFP; + + write_sysreg(val, cptr_el2); } +} - if (!guest_owns_fp_regs(vcpu)) - __activate_traps_fpsimd32(vcpu); +static void __deactivate_cptr_traps(struct kvm_vcpu *vcpu) +{ + if (has_hvhe()) { + u64 val = CPACR_ELx_FPEN; + + if (cpus_have_final_cap(ARM64_SVE)) + val |= CPACR_ELx_ZEN; + if (cpus_have_final_cap(ARM64_SME)) + val |= CPACR_ELx_SMEN; + + write_sysreg(val, cpacr_el1); + } else { + u64 val = CPTR_NVHE_EL2_RES1; + + if (!cpus_have_final_cap(ARM64_SVE)) + val |= CPTR_EL2_TZ; + if (!cpus_have_final_cap(ARM64_SME)) + val |= CPTR_EL2_TSM; - kvm_write_cptr_el2(val); + write_sysreg(val, cptr_el2); + } } static void __activate_traps(struct kvm_vcpu *vcpu) @@ -120,7 +145,7 @@ static void __deactivate_traps(struct kv write_sysreg(this_cpu_ptr(&kvm_init_params)->hcr_el2, hcr_el2); - kvm_reset_cptr_el2(vcpu); + __deactivate_cptr_traps(vcpu); write_sysreg(__kvm_hyp_host_vector, vbar_el2); } --- a/arch/arm64/kvm/hyp/vhe/switch.c +++ b/arch/arm64/kvm/hyp/vhe/switch.c @@ -212,6 +212,8 @@ static int __kvm_vcpu_run_vhe(struct kvm sysreg_save_host_state_vhe(host_ctxt); + fpsimd_lazy_switch_to_guest(vcpu); + /* * ARM erratum 1165522 requires us to configure both stage 1 and * stage 2 translation for the guest context before we clear @@ -247,6 +249,8 @@ static int __kvm_vcpu_run_vhe(struct kvm __deactivate_traps(vcpu); + fpsimd_lazy_switch_to_host(vcpu); + sysreg_restore_host_state_vhe(host_ctxt); if (vcpu->arch.fp_state == FP_STATE_GUEST_OWNED) --- a/arch/arm64/kvm/reset.c +++ b/arch/arm64/kvm/reset.c @@ -46,11 +46,14 @@ static u32 __ro_after_init kvm_ipa_limit PSR_AA32_I_BIT | PSR_AA32_F_BIT) unsigned int __ro_after_init kvm_sve_max_vl; +unsigned int __ro_after_init kvm_host_sve_max_vl; int __init kvm_arm_init_sve(void) { if (system_supports_sve()) { kvm_sve_max_vl = sve_max_virtualisable_vl(); + kvm_host_sve_max_vl = sve_max_vl(); + kvm_nvhe_sym(kvm_host_sve_max_vl) = kvm_host_sve_max_vl; /* * The get_sve_reg()/set_sve_reg() ioctl interface will need Patches currently in stable-queue which might be from broonie@kernel.org are queue-6.6/kvm-arm64-calculate-cptr_el2-traps-on-activating-traps.patch queue-6.6/regulator-check-that-dummy-regulator-has-been-probed-before-using-it.patch queue-6.6/kvm-arm64-eagerly-switch-zcr_el-1-2.patch queue-6.6/kvm-arm64-mark-some-header-functions-as-inline.patch queue-6.6/kvm-arm64-remove-host-fpsimd-saving-for-non-protected-kvm.patch queue-6.6/regulator-dummy-force-synchronous-probing.patch queue-6.6/kvm-arm64-refactor-exit-handlers.patch queue-6.6/kvm-arm64-unconditionally-save-flush-host-fpsimd-sve-sme-state.patch queue-6.6/kvm-arm64-remove-vhe-host-restore-of-cpacr_el1.smen.patch queue-6.6/kvm-arm64-remove-vhe-host-restore-of-cpacr_el1.zen.patch