From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pg1-f201.google.com (mail-pg1-f201.google.com [209.85.215.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 21C4C34575F for ; Tue, 21 Oct 2025 16:56:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.215.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761065783; cv=none; b=SSy4O4plQYb76qmh6KFMIKt+qr9E9LNaeKwd0sRHW9+fOxjjM1TecuzMlzsHltP/LTdfNWY10Y9zbx6RPRzpKseGGM73mU0cWukGSsTqBEAG6uUqa9sCjegTm0ZCkaPbKlEidZYGaJbbiwHIZDmNMw+0/4agJzoc22nrm3C6zKg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761065783; c=relaxed/simple; bh=RDkmhC4PKjh9lbEZgOEdown78rPWmXw4ycUHNJGAVxA=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=iahgJqpXifbnJG02JtPDI0htHjMNemyI1qw/6rv8sSqBNeE1KZafAImGbMcTHDrzGQ5HlOdhLhCgD1YH8c3v3ceHby/JnwsUdyXt1qgbQmZ5js9m1kvPfer4ade4yM2ZqIWqiJAv5Kw30X0D/j3ayTm1a248fUMVwxvM/UUoePU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=nUwNyp0A; arc=none smtp.client-ip=209.85.215.201 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="nUwNyp0A" Received: by mail-pg1-f201.google.com with SMTP id 41be03b00d2f7-b5533921eb2so3654659a12.0 for ; Tue, 21 Oct 2025 09:56:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1761065781; x=1761670581; darn=lists.linux.dev; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=QUj6Jzqtl7pAwgzbknudC50aTFamgZNMeXgKkiBAGZE=; b=nUwNyp0ASOFk3o4Xy5bhf5hGZDNZE+BOUZxjY7dHBwuwGIkWBq3ofMB6CMKZ4M/z78 0RsfaPA+P6H5a6rixofLEB0a8Fb6WNtRs3lbSQVY2C7OA3joJ3+sINGCSzfAPvqQ56/q 2bD/A505V/iTgiwnEeSKBuGb/bLJ+Hk/0YAT28EiG12G09l4YtgzYhu0rzDuyAqcnhSY AfLMNVDknZFMRuPlXxm0xmIFRNglwYQE1mVz2hPyFXiKLFSbYzaWP1eMPrprltRitYtb f0YdWc5u/0RoTOJ7wwAoxQhbCzq1WZGrzLDhTv7tF3mH/i4CexsVn5Lnb3SSg+myWVRu YWtg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1761065781; x=1761670581; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=QUj6Jzqtl7pAwgzbknudC50aTFamgZNMeXgKkiBAGZE=; b=BENfZ5P6amPiivXk2NNvZ3e4LdwQq8EIcdsq5ItC5P1FJyr898Q8nRlvSH2w3dOTbb amE0RP0Yvelkkm2uJwcOf3obRmjJSMTiCXbQDJfonn4kE1SVZQflZFnNlD1Uh2aPirmY 3SakEiOrVK3dpsMtYBPzTDAz0rfNvkI1R5tmxCI0DMx4rgyLDr5jMeZdGh8w1LLlLj8a 764ZdcDFDLcq0zOwskpugTXpeOEP/mfONO7d59o3uOrjJpCzOZRdDgLB9w5wpmIljNuh 81C6KDC3hjabzflii2mU2x4XhTRkLc1f35rwzd4zMzhCXwQE52IkMt088wyERag2cxyP Urpw== X-Forwarded-Encrypted: i=1; AJvYcCXIHUXi+u2OCANKaerB8h3io3m6EVqgPH33XMDK/YhWDl4wKQ+YllTHyIcgKWtBifkPNhGRPPkabU1s@lists.linux.dev X-Gm-Message-State: AOJu0Yxna+wJTSLean7RxvjbD8okmsY0wL+Sw/1a+50pQVE7O+4zAFAQ zSHSCpd3cq0J8gcp7558n2Od2TUCqrSDiT7YEYIXXqP4LJZQQoWr7G1NSsgjBJAvP+BhVJMdA+r zz16ddA== X-Google-Smtp-Source: AGHT+IGOqKmUzCbfjGYr8B2jY/C1mdIZnvxK8+ss+AVkwVotQdjiGEd+3SJ7VfMTaFoQGYSh7+8f99sR5n0= X-Received: from pjre3.prod.google.com ([2002:a17:90a:b383:b0:33b:51fe:1a75]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:902:e88e:b0:250:1c22:e78 with SMTP id d9443c01a7336-290c9c89c9amr235880025ad.1.1761065780727; Tue, 21 Oct 2025 09:56:20 -0700 (PDT) Date: Tue, 21 Oct 2025 09:56:19 -0700 In-Reply-To: Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20251017003244.186495-1-seanjc@google.com> <20251017003244.186495-24-seanjc@google.com> Message-ID: Subject: Re: [PATCH v3 23/25] KVM: TDX: Use guard() to acquire kvm->lock in tdx_vm_ioctl() From: Sean Christopherson To: Rick P Edgecombe Cc: "chenhuacai@kernel.org" , "frankja@linux.ibm.com" , "maz@kernel.org" , "borntraeger@linux.ibm.com" , "pjw@kernel.org" , "aou@eecs.berkeley.edu" , "kas@kernel.org" , "maobibo@loongson.cn" , "pbonzini@redhat.com" , "maddy@linux.ibm.com" , "palmer@dabbelt.com" , "imbrenda@linux.ibm.com" , "zhaotianrui@loongson.cn" , "anup@brainfault.org" , "oliver.upton@linux.dev" , "kvm@vger.kernel.org" , "linux-coco@lists.linux.dev" , Kai Huang , Yan Y Zhao , "michael.roth@amd.com" , "linux-kernel@vger.kernel.org" , Ira Weiny , "loongarch@lists.linux.dev" , "binbin.wu@linux.intel.com" , "ackerleytng@google.com" , "kvmarm@lists.linux.dev" , Vishal Annapurve , "kvm-riscv@lists.infradead.org" , "linuxppc-dev@lists.ozlabs.org" , "linux-arm-kernel@lists.infradead.org" , "linux-mips@vger.kernel.org" , "linux-riscv@lists.infradead.org" , "x86@kernel.org" Content-Type: text/plain; charset="us-ascii" On Tue, Oct 21, 2025, Rick P Edgecombe wrote: > On Thu, 2025-10-16 at 17:32 -0700, Sean Christopherson wrote: > > Use guard() in tdx_vm_ioctl() to tidy up the code a small amount, but more > > importantly to minimize the diff of a future change, which will use > > guard-like semantics to acquire and release multiple locks. > > > > No functional change intended. > > There is a tiny functional change. In the default case it no longer re-copies > the struct back to userspace. No? The default case doesn't copy the struct back even before this patch, it explicitly skips the copy_to_user(). mutex_lock(&kvm->lock); switch (tdx_cmd.id) { case KVM_TDX_CAPABILITIES: r = tdx_get_capabilities(&tdx_cmd); break; case KVM_TDX_INIT_VM: r = tdx_td_init(kvm, &tdx_cmd); break; case KVM_TDX_FINALIZE_VM: r = tdx_td_finalize(kvm, &tdx_cmd); break; default: r = -EINVAL; goto out; <==================== } if (copy_to_user(argp, &tdx_cmd, sizeof(struct kvm_tdx_cmd))) r = -EFAULT; out: mutex_unlock(&kvm->lock); return r;