From mboxrd@z Thu Jan 1 00:00:00 1970 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 9AA048F64 for ; Sat, 5 Apr 2025 11:57:42 +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=1743854262; cv=none; b=TwrK81GJsSO43/jUtk8nfMNKNY0UmJ35+S7u/4UVAooh0vpk46sJhr9RSF+eCMUr43uDpqcdAqFHIAcgCu/NIlsd41SKM2Mfw58EjrEdZPMPOqfJ4TYzMbwCMG8Zonjq8DVuZXeM9bFbDeVYBCTLJtBHUhdIEJIGaIm+cpncndg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743854262; c=relaxed/simple; bh=+Z1qV6U25FbFpcUCZxwJfiinh+rInJ6lNZPx6QSauvI=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version:Content-Type; b=m1x9zTAF0EG7FgyTYRO9kcHSS6vNxOe3YcnfIONLqx715HcgJovpFi3Wo8dc6rj7giVLjpYstYoWBexRFu/BkhowId047LnztAT8p5svYTh4p8WAqLiBFEt7tuCUAdcG52TYHbPHQF0t1ej7Y50mNEaiXlLJl8ldi3dDiEq63lk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=GGZ6Z7FS; 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="GGZ6Z7FS" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A03AEC4CEE4; Sat, 5 Apr 2025 11:57:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1743854262; bh=+Z1qV6U25FbFpcUCZxwJfiinh+rInJ6lNZPx6QSauvI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=GGZ6Z7FSbCkcgB/lVYA1120Mtv+hkv5IBfM04H5svnxl8mmeSz5nxueLd97V4YtzF W0SYsdnLkbUoLqGMjb5UJTIu2cnFtt3Z3gpW1yCKwJXhaKRoE+VgM4BWXRlGZHoo61 zenLPoB45Ws1y2wAYJOT41Vo8ClosVKNKALG5MCGpt91j6Xy0tauoImnI9PpSxm2kh 9+44Ktif8oxJMyBZSFBZQ7MITjuQi3TwA5fVnDHWmSS23ogLgVfv17pkNpu440lYMM +ffVxlQ09L6GNCl2O+yaCTWaEld2ViGhUqfBVgDMgUAoL94GzvpN8kk4EtbKEy2zSQ k1l9nkE9fXu0A== From: Sasha Levin To: stable@vger.kernel.org Cc: Mark Brown , Sasha Levin Subject: Re: [PATCH RESEND 6.1 05/12] KVM: arm64: Unconditionally save+flush host FPSIMD/SVE/SME state Date: Sat, 5 Apr 2025 07:57:40 -0400 Message-Id: <20250405015521-66b5d71f62fa5217@stable.kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250404-stable-sve-6-1-v1-5-cd5c9eb52d49@kernel.org> References: Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit [ Sasha's backport helper bot ] Hi, ✅ All tests passed successfully. No issues detected. No action required from the submitter. The upstream commit SHA1 provided is correct: fbc7e61195e23f744814e78524b73b59faa54ab4 WARNING: Author mismatch between patch and upstream commit: Backport author: Mark Brown Commit author: Mark Rutland Status in newer kernel trees: 6.14.y | Present (exact SHA1) 6.13.y | Present (different SHA1: 900b444be493) 6.12.y | Present (different SHA1: 79e140bba70b) 6.6.y | Present (different SHA1: 806d5c1e1d2e) Note: The patch differs from the upstream commit: --- 1: fbc7e61195e23 ! 1: 46b6201d09cb2 KVM: arm64: Unconditionally save+flush host FPSIMD/SVE/SME state @@ Metadata ## Commit message ## KVM: arm64: Unconditionally save+flush host FPSIMD/SVE/SME state + [ Upstream commit fbc7e61195e23f744814e78524b73b59faa54ab4 ] + There are several problems with the way hyp code lazily saves the host's FPSIMD/SVE state, including: @@ Commit message 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, remove host_data_ptr() ] + Signed-off-by: Mark Rutland + Signed-off-by: Mark Brown ## arch/arm64/kernel/fpsimd.c ## @@ arch/arm64/kernel/fpsimd.c: void fpsimd_signal_preserve_current_state(void) @@ arch/arm64/kvm/fpsimd.c: void kvm_arch_vcpu_load_fp(struct kvm_vcpu *vcpu) - 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. +- vcpu->arch.fp_state = FP_STATE_HOST_OWNED; ++ /* + * 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}. - */ -- *host_data_ptr(fp_owner) = FP_STATE_HOST_OWNED; -- *host_data_ptr(fpsimd_state) = kern_hyp_va(¤t->thread.uw.fpsimd_state); -- *host_data_ptr(fpmr_ptr) = kern_hyp_va(¤t->thread.uw.fpmr); ++ */ + fpsimd_save_and_flush_cpu_state(); -+ *host_data_ptr(fp_owner) = FP_STATE_FREE; -+ *host_data_ptr(fpsimd_state) = NULL; -+ *host_data_ptr(fpmr_ptr) = NULL; ++ vcpu->arch.fp_state = FP_STATE_FREE; - host_data_clear_flag(HOST_SVE_ENABLED); + vcpu_clear_flag(vcpu, HOST_SVE_ENABLED); if (read_sysreg(cpacr_el1) & CPACR_EL1_ZEN_EL0EN) @@ arch/arm64/kvm/fpsimd.c: void kvm_arch_vcpu_load_fp(struct kvm_vcpu *vcpu) - host_data_clear_flag(HOST_SME_ENABLED); + vcpu_clear_flag(vcpu, HOST_SME_ENABLED); if (read_sysreg(cpacr_el1) & CPACR_EL1_SMEN_EL0EN) - host_data_set_flag(HOST_SME_ENABLED); + 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)) { -- *host_data_ptr(fp_owner) = FP_STATE_FREE; +- vcpu->arch.fp_state = FP_STATE_FREE; - fpsimd_save_and_flush_cpu_state(); - } } + } - /* --- Results of testing on various branches: | Branch | Patch Apply | Build Test | |---------------------------|-------------|------------| | stable/linux-6.6.y | Success | Success |