From nobody Sat Apr 4 01:17:44 2026 Received: from mail.loongson.cn (mail.loongson.cn [114.242.206.163]) by smtp.subspace.kernel.org (Postfix) with ESMTP id AA3BB299937; Mon, 23 Mar 2026 02:56:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=114.242.206.163 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774234583; cv=none; b=WPDA+sZL+sRtn9zyyh5zB4LwvI8ajIpUrVhNMTXbqTEipqGxAD6ehk8r895arduY2PiTaSaOk8EEpR8k6HS+pZnNsn0OthL4ok+29MZKDNK24Ju+kUEcV9lTp57SmjIJ5qmxVQYBLCUixVkwSVsUzk0TPXdzdQjLucK1N2dIf+o= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774234583; c=relaxed/simple; bh=vJn81t4uxYYWNgXRhGeseiQqdg75Zy7PleMWDkS5N6M=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=jbwV4k0k+GUo2Brkr+8X+CP8Rru6GbjN59B24tCMTdihjgSVL4XwP/9NSnh0FCG55OXhLPPxTZY+xnfkb2fSdqbBxojmBM/7GGbbXGBV2FwDSPa1sLn5Dc1fKU8Ux0yIPE6cIZINC4AuLpmuv7bu5aODfT660Cf1rjez4kyg2jg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=loongson.cn; spf=pass smtp.mailfrom=loongson.cn; arc=none smtp.client-ip=114.242.206.163 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=loongson.cn Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=loongson.cn Received: from loongson.cn (unknown [10.2.5.213]) by gateway (Coremail) with SMTP id _____8DxssDTq8BppqYdAA--.25936S3; Mon, 23 Mar 2026 10:56:19 +0800 (CST) Received: from localhost.localdomain (unknown [10.2.5.213]) by front1 (Coremail) with SMTP id qMiowJBxbcLOq8Bpcg5bAA--.40805S5; Mon, 23 Mar 2026 10:56:17 +0800 (CST) From: Bibo Mao To: Tianrui Zhao , Huacai Chen Cc: kernel@xen0n.name, kvm@vger.kernel.org, loongarch@lists.linux.dev, linux-kernel@vger.kernel.org, Juergen Gross Subject: [PATCH v3 3/4] LoongArch: KVM: Move host CSR_GSTAT save and restore in context switch Date: Mon, 23 Mar 2026 10:56:12 +0800 Message-Id: <20260323025613.3260876-4-maobibo@loongson.cn> X-Mailer: git-send-email 2.39.3 In-Reply-To: <20260323025613.3260876-1-maobibo@loongson.cn> References: <20260323025613.3260876-1-maobibo@loongson.cn> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: qMiowJBxbcLOq8Bpcg5bAA--.40805S5 X-CM-SenderInfo: xpdruxter6z05rqj20fqof0/ X-Coremail-Antispam: 1Uk129KBjDUn29KB7ZKAUJUUUUU529EdanIXcx71UUUUU7KY7 ZEXasCq-sGcSsGvfJ3UbIjqfuFe4nvWSU5nxnvy29KBjDU0xBIdaVrnUUvcSsGvfC2Kfnx nUUI43ZEXa7xR_UUUUUUUUU== Content-Type: text/plain; charset="utf-8" CSR register CSR_GSTAT stores guest VMID information. With existing implementation method, VMID is per vCPU similar with ASID on kernel. Register CSR_GSTAT is written at VM entry even if VMID is not changed. Here move CSR_GSTAT save/restore in vCPU context switch, and update register CSR_GSTAT only when VMID is updated at VM entry. At most time VM enter/exit is much more frequent than vCPU thread context switch. Signed-off-by: Bibo Mao --- arch/loongarch/kvm/main.c | 8 ++++---- arch/loongarch/kvm/vcpu.c | 2 ++ 2 files changed, 6 insertions(+), 4 deletions(-) diff --git a/arch/loongarch/kvm/main.c b/arch/loongarch/kvm/main.c index 2c593ac7892f..304c83863e71 100644 --- a/arch/loongarch/kvm/main.c +++ b/arch/loongarch/kvm/main.c @@ -271,11 +271,11 @@ void kvm_check_vpid(struct kvm_vcpu *vcpu) * memory with new address is changed on other VCPUs. */ set_gcsr_llbctl(CSR_LLBCTL_WCLLB); - } =20 - /* Restore GSTAT(0x50).vpid */ - vpid =3D (vcpu->arch.vpid & vpid_mask) << CSR_GSTAT_GID_SHIFT; - change_csr_gstat(vpid_mask << CSR_GSTAT_GID_SHIFT, vpid); + /* Restore GSTAT(0x50).vpid */ + vpid =3D (vcpu->arch.vpid & vpid_mask) << CSR_GSTAT_GID_SHIFT; + change_csr_gstat(vpid_mask << CSR_GSTAT_GID_SHIFT, vpid); + } } =20 void kvm_init_vmcs(struct kvm *kvm) diff --git a/arch/loongarch/kvm/vcpu.c b/arch/loongarch/kvm/vcpu.c index e82b2c84ce17..8810fcd7e26e 100644 --- a/arch/loongarch/kvm/vcpu.c +++ b/arch/loongarch/kvm/vcpu.c @@ -1695,6 +1695,7 @@ static int _kvm_vcpu_load(struct kvm_vcpu *vcpu, int = cpu) =20 /* Restore Root.GINTC from unused Guest.GINTC register */ write_csr_gintc(csr->csrs[LOONGARCH_CSR_GINTC]); + write_csr_gstat(csr->csrs[LOONGARCH_CSR_GSTAT]); =20 /* * We should clear linked load bit to break interrupted atomics. This @@ -1790,6 +1791,7 @@ static int _kvm_vcpu_put(struct kvm_vcpu *vcpu, int c= pu) kvm_save_hw_gcsr(csr, LOONGARCH_CSR_ISR3); } =20 + csr->csrs[LOONGARCH_CSR_GSTAT] =3D read_csr_gstat(); vcpu->arch.aux_inuse |=3D KVM_LARCH_SWCSR_LATEST; =20 out: --=20 2.39.3