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 0E9E1C35FFC for ; Tue, 25 Mar 2025 11:42:55 +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=oc7oO3qa99lDUnYlLoi/lJ66SqP1JthXdSMHgbhDaIs=; b=s1t45foWqhFaeweld2MqjQfJfb x+rU+aPuDfM51a5KEwcuq971iaIR1MH4iZZqqOi1sDGFGzWOs9L8LNn/aV2zn35xxCzjvnilKGZYU 0pcnooxL/Zi2MvqEhAdEfFfoF37ZsqqL6x+yukQPJRqLx+MkKrCp7Ox0SXb00ssWr2643XdIToJEv zytEaRZy7GC0+7swzU3fg8l4t+a79QvdRUcTvvh5Hm/UFyJyc4BCEtb0GncbzUt39fbnhIUhJlTe+ QF1JLr5G0/LNdfiwvh4Z09aJUpRs0jzSQ5UhnFqR3pUJ/hPwovR/U3AQXYSZtg4b/X4NVV4EapZe/ Ko2eELlw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.1 #2 (Red Hat Linux)) id 1tx2g3-00000005fkn-2c9o; Tue, 25 Mar 2025 11:42:39 +0000 Received: from tor.source.kernel.org ([172.105.4.254]) by bombadil.infradead.org with esmtps (Exim 4.98.1 #2 (Red Hat Linux)) id 1tx2UP-00000005djo-1N9S for linux-arm-kernel@lists.infradead.org; Tue, 25 Mar 2025 11:30:37 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id 6E30461587; Tue, 25 Mar 2025 11:30:32 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 17BE0C4CEE4; Tue, 25 Mar 2025 11:30:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1742902236; bh=svxE9d4fPdiow20B9GTk84FAT9EgcWECPw7A2j8U/Cg=; h=Subject:To:Cc:From:Date:In-Reply-To:From; b=rZ2yyLZheGJfLNcxP8GY3mbdqwQ9nQHO/fiZqODWRAUUZ7hPSNzdbvHP/N65a38RY Zp9+mtTClH5jYEL9lMoLlYUKOQLArHN+bu8JwYWrVQSdIpe6ub+JQn+p6WfUdeVU6z QNU744x4p+JBWMC/yTMLc9SXZnY3on2JlCE6PLZg= Subject: Patch "KVM: arm64: Unconditionally save+flush host FPSIMD/SVE/SME state" has been added to the 6.6-stable tree To: broonie@kernel.org,catalin.marinas@arm.com,eauger@redhat.com,eric.auger@redhat.com,fweimer@redhat.com,gregkh@linuxfoundation.org,james.morse@arm.com,jeremy.linton@arm.com,kvmarm@lists.linux.dev,linux-arm-kernel@lists.infradead.org,mark.rutland@arm.com,maz@kernel.org,oliver.upton@linux.dev,pbonzini@redhat.com,suzuki.poulose@arm.com,tabba@google.com,wilco.dijkstra@arm.com,will@kernel.org Cc: From: Date: Tue, 25 Mar 2025 07:28:56 -0400 In-Reply-To: <20250321-stable-sve-6-6-v1-2-0b3a6a14ea53@kernel.org> Message-ID: <2025032556-jingling-scope-be6f@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-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: Unconditionally save+flush host FPSIMD/SVE/SME state 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-unconditionally-save-flush-host-fpsimd-sve-sme-state.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 stable+bounces-125720-greg=kroah.com@vger.kernel.org Thu Mar 20 20:18:53 2025 From: Mark Brown Date: Fri, 21 Mar 2025 00:16:02 +0000 Subject: KVM: arm64: Unconditionally save+flush host FPSIMD/SVE/SME state 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 , Eric Auger , Wilco Dijkstra , Eric Auger , Florian Weimer , Fuad Tabba , Jeremy Linton , Paolo Bonzini Message-ID: <20250321-stable-sve-6-6-v1-2-0b3a6a14ea53@kernel.org> From: Mark Rutland [ Upstream commit fbc7e61195e23f744814e78524b73b59faa54ab4 ] There are several problems with the way hyp code lazily saves the host's FPSIMD/SVE state, including: * Host SVE being discarded unexpectedly due to inconsistent configuration of TIF_SVE and CPACR_ELx.ZEN. This has been seen to result in QEMU crashes where SVE is used by memmove(), as reported by Eric Auger: https://issues.redhat.com/browse/RHEL-68997 * Host SVE state is discarded *after* modification by ptrace, which was an unintentional ptrace ABI change introduced with lazy discarding of SVE state. * The host FPMR value can be discarded when running a non-protected VM, where FPMR support is not exposed to a VM, and that VM uses FPSIMD/SVE. In these cases the hyp code does not save the host's FPMR before unbinding the host's FPSIMD/SVE/SME state, leaving a stale value in memory. Avoid these by eagerly saving and "flushing" the host's FPSIMD/SVE/SME state when loading a vCPU such that KVM does not need to save any of the host's FPSIMD/SVE/SME state. For clarity, fpsimd_kvm_prepare() is removed and the necessary call to fpsimd_save_and_flush_cpu_state() is placed in kvm_arch_vcpu_load_fp(). As 'fpsimd_state' and 'fpmr_ptr' should not be used, they are set to NULL; all uses of these will be removed in subsequent patches. Historical problems go back at least as far as v5.17, e.g. erroneous assumptions about TIF_SVE being clear in commit: 8383741ab2e773a9 ("KVM: arm64: Get rid of host SVE tracking/saving") ... and so this eager save+flush probably needs to be backported to ALL stable trees. Fixes: 93ae6b01bafee8fa ("KVM: arm64: Discard any SVE state when entering KVM guests") Fixes: 8c845e2731041f0f ("arm64/sve: Leave SVE enabled on syscall if we don't context switch") Fixes: ef3be86021c3bdf3 ("KVM: arm64: Add save/restore support for FPMR") Reported-by: Eric Auger Reported-by: Wilco Dijkstra Reviewed-by: Mark Brown Tested-by: Mark Brown Tested-by: Eric Auger Acked-by: Will Deacon Cc: Catalin Marinas Cc: Florian Weimer Cc: Fuad Tabba Cc: Jeremy Linton Cc: Marc Zyngier Cc: Oliver Upton Cc: Paolo Bonzini Signed-off-by: Mark Rutland Reviewed-by: Oliver Upton Link: https://lore.kernel.org/r/20250210195226.1215254-2-mark.rutland@arm.com Signed-off-by: Marc Zyngier [ Mark: Handle vcpu/host flag conflict ] Signed-off-by: Mark Rutland Signed-off-by: Mark Brown Signed-off-by: Greg Kroah-Hartman --- arch/arm64/kernel/fpsimd.c | 25 ------------------------- arch/arm64/kvm/fpsimd.c | 31 ++++++++----------------------- 2 files changed, 8 insertions(+), 48 deletions(-) --- a/arch/arm64/kernel/fpsimd.c +++ b/arch/arm64/kernel/fpsimd.c @@ -1708,31 +1708,6 @@ void fpsimd_signal_preserve_current_stat } /* - * Called by KVM when entering the guest. - */ -void fpsimd_kvm_prepare(void) -{ - if (!system_supports_sve()) - return; - - /* - * KVM does not save host SVE state since we can only enter - * the guest from a syscall so the ABI means that only the - * non-saved SVE state needs to be saved. If we have left - * SVE enabled for performance reasons then update the task - * state to be FPSIMD only. - */ - get_cpu_fpsimd_context(); - - if (test_and_clear_thread_flag(TIF_SVE)) { - sve_to_fpsimd(current); - current->thread.fp_type = FP_STATE_FPSIMD; - } - - put_cpu_fpsimd_context(); -} - -/* * Associate current's FPSIMD context with this cpu * The caller must have ownership of the cpu FPSIMD context before calling * this function. --- a/arch/arm64/kvm/fpsimd.c +++ b/arch/arm64/kvm/fpsimd.c @@ -79,14 +79,16 @@ void kvm_arch_vcpu_load_fp(struct kvm_vc if (!system_supports_fpsimd()) return; - fpsimd_kvm_prepare(); - /* - * We will check TIF_FOREIGN_FPSTATE just before entering the - * guest in kvm_arch_vcpu_ctxflush_fp() and override this to - * FP_STATE_FREE if the flag set. + * Ensure that any host FPSIMD/SVE/SME state is saved and unbound such + * that the host kernel is responsible for restoring this state upon + * return to userspace, and the hyp code doesn't need to save anything. + * + * When the host may use SME, fpsimd_save_and_flush_cpu_state() ensures + * that PSTATE.{SM,ZA} == {0,0}. */ - vcpu->arch.fp_state = FP_STATE_HOST_OWNED; + fpsimd_save_and_flush_cpu_state(); + vcpu->arch.fp_state = FP_STATE_FREE; vcpu_clear_flag(vcpu, HOST_SVE_ENABLED); if (read_sysreg(cpacr_el1) & CPACR_EL1_ZEN_EL0EN) @@ -96,23 +98,6 @@ void kvm_arch_vcpu_load_fp(struct kvm_vc vcpu_clear_flag(vcpu, HOST_SME_ENABLED); if (read_sysreg(cpacr_el1) & CPACR_EL1_SMEN_EL0EN) vcpu_set_flag(vcpu, HOST_SME_ENABLED); - - /* - * If PSTATE.SM is enabled then save any pending FP - * state and disable PSTATE.SM. If we leave PSTATE.SM - * enabled and the guest does not enable SME via - * CPACR_EL1.SMEN then operations that should be valid - * may generate SME traps from EL1 to EL1 which we - * can't intercept and which would confuse the guest. - * - * Do the same for PSTATE.ZA in the case where there - * is state in the registers which has not already - * been saved, this is very unlikely to happen. - */ - if (read_sysreg_s(SYS_SVCR) & (SVCR_SM_MASK | SVCR_ZA_MASK)) { - vcpu->arch.fp_state = FP_STATE_FREE; - fpsimd_save_and_flush_cpu_state(); - } } } 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