From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pg1-f202.google.com (mail-pg1-f202.google.com [209.85.215.202]) (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 E7F702EAF7 for ; Sat, 19 Apr 2025 01:12:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.215.202 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745025145; cv=none; b=MN3Tg65veigUr6jxw7MqhPbSIAZYBjNrqZoH4LyrUPcLKHXctQa0R3dY10KHiW9H/fM6piM5RH3glccFjydAPJUEH3pDmP2Yf3K1Rk0KMit1x7gN+eS3wUciRW3YiibkaO9D+vqiz+zG7uaVrw/95+iHKg+0/cKLQJcoxxrsYbA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745025145; c=relaxed/simple; bh=GBLqjUBIYKLE1OiCMwpLkALClRqsAbp12xJDCFy7CyM=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=KO19nI3X1joF9decqTNPAZE47poi3op6ec/5jXjzNLiRGhtnFEbJYjbZ7scJr32T8GpR/AuujdHfXzgV6egBI9rox1lDBuBSj66LjdjXCZc3NJq9PWUZ7mUwcNL+3K+NONNT67LeBUYao055Hmc/7gRPdD9HnIyZJgT1OtTqanw= 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=B8NlNWB9; arc=none smtp.client-ip=209.85.215.202 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="B8NlNWB9" Received: by mail-pg1-f202.google.com with SMTP id 41be03b00d2f7-afd1e7f52f7so1412722a12.1 for ; Fri, 18 Apr 2025 18:12:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1745025143; x=1745629943; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=bAssG5fQ67XkPLJgYAAQI+PG7StKquP6G71qrzqZJ2M=; b=B8NlNWB9phPpWgL7/BxpPv4URlLClC8a0BEX+08PszdC9jUUFs1fQ1Fk/tsLb6l0t2 YoxZ4nxsO60XwxQ4HhC7KKBjTAax118XmJ+zOCGNDc1bk6W/2PK1x60ipv5zZ7rGRSnN HayPgA5I56VdRi2WxZ0A+U0i+I8+TvuQI1rDHd9ljGX4GqhX3qMCk4oMR6tGrNLz23Wj cpTJXWBPjm8+NQk3R2ttmv9Q+WJ7EIlTPw0nxrVmNH4n3jHu9Oj1QmFSJaIGckXMDVQz O2BQsOmRhd4pUeLp0C5O/UYrIfEs/lHPJb5lTZwjj3ErEwanO1j8zc33Vd/aaVbG+R21 +FSg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1745025143; x=1745629943; 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=bAssG5fQ67XkPLJgYAAQI+PG7StKquP6G71qrzqZJ2M=; b=TANoKUUNjSRb7SpbIfBaHScUNmM2zj1yUmg8OIgEUJ+/CV7bRfJml27W4xu4maaZmn 5BW72yaBOHzIy3nbOJ/stRkOCv8n7H4H5iqxkTTc6MwQKHQ2W2760aHvfNzBel9RMfgE 8NvFajm5WPaKWyejoH/x733vVbyYg4BQ4XUgu4oxLpaPN5ozdUMNZqFDnzc623WCpLds 09Y7xLupdSt861010UmjOWaC5X9jMMnkR9z0hkTQszpoyfi3nwjdYLY2W4803WX/Vj5X EwFkax58BAAPWHwivRPRU/f/xU4DVrPw6hHKkViBFKFm4BD+UH9GfJ5hievgJ6mux3nw mfYg== X-Forwarded-Encrypted: i=1; AJvYcCUdalWHXHNeK63Qsw3TU1wXJ2oohFzZBmoN/8XBiVQONU1SO6VXEm/9JnoSOOCBE2RBQLk=@vger.kernel.org X-Gm-Message-State: AOJu0Yzr6Qq8D59G4Ybjq7AoHgo/CcC3okJQrfYuJ+Lcyuq8QKz4vqnu zX+vEdutpnOzUXLuQiiS4AL/7mPXPHNplu4uOc0WLqSI94bkeFaFfMKxmdGl5comTxSkvmI1+1o m7w== X-Google-Smtp-Source: AGHT+IEwiOscwRryNbV5HEkDLR/QSN5uMa5G6pQrJMGE0vv7idD4Yujycc133PfZgsKp3+f0KyatWMvuqqA= X-Received: from pjwx11.prod.google.com ([2002:a17:90a:c2cb:b0:2ea:29de:af10]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:902:ef11:b0:224:2384:5b40 with SMTP id d9443c01a7336-22c535a7e46mr72675585ad.24.1745025143192; Fri, 18 Apr 2025 18:12:23 -0700 (PDT) Date: Fri, 18 Apr 2025 18:12:21 -0700 In-Reply-To: <20250417131945.109053-2-adrian.hunter@intel.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250417131945.109053-1-adrian.hunter@intel.com> <20250417131945.109053-2-adrian.hunter@intel.com> Message-ID: Subject: Re: [PATCH V2 1/1] KVM: TDX: Add sub-ioctl KVM_TDX_TERMINATE_VM From: Sean Christopherson To: Adrian Hunter Cc: pbonzini@redhat.com, mlevitsk@redhat.com, kvm@vger.kernel.org, rick.p.edgecombe@intel.com, kirill.shutemov@linux.intel.com, kai.huang@intel.com, reinette.chatre@intel.com, xiaoyao.li@intel.com, tony.lindgren@linux.intel.com, binbin.wu@linux.intel.com, isaku.yamahata@intel.com, linux-kernel@vger.kernel.org, yan.y.zhao@intel.com, chao.gao@intel.com Content-Type: text/plain; charset="us-ascii" On Thu, Apr 17, 2025, Adrian Hunter wrote: > From: Sean Christopherson > > Add sub-ioctl KVM_TDX_TERMINATE_VM to release the HKID prior to shutdown, > which enables more efficient reclaim of private memory. > > Private memory is removed from MMU/TDP when guest_memfds are closed. If > the HKID has not been released, the TDX VM is still in RUNNABLE state, > so pages must be removed using "Dynamic Page Removal" procedure (refer > TDX Module Base spec) which involves a number of steps: > Block further address translation > Exit each VCPU > Clear Secure EPT entry > Flush/write-back/invalidate relevant caches > > However, when the HKID is released, the TDX VM moves to TD_TEARDOWN state > where all TDX VM pages are effectively unmapped, so pages can be reclaimed > directly. > > Reclaiming TD Pages in TD_TEARDOWN State was seen to decrease the total > reclaim time. For example: > > VCPUs Size (GB) Before (secs) After (secs) > 4 18 72 24 > 32 107 517 134 > 64 400 5539 467 > > [Adrian: wrote commit message, added KVM_TDX_TERMINATE_VM documentation, > and moved cpus_read_lock() inside kvm->lock for consistency as reported > by lockdep] /facepalm I over-thought this. We've had an long-standing battle with kvm_lock vs. cpus_read_lock(), but this is kvm->lock, not kvm_lock. /sigh > +static int tdx_terminate_vm(struct kvm *kvm) > +{ > + int r = 0; > + > + guard(mutex)(&kvm->lock); With kvm->lock taken outside cpus_read_lock(), just handle KVM_TDX_TERMINATE_VM in the switch statement, i.e. let tdx_vm_ioctl() deal with kvm->lock. > + cpus_read_lock(); > + > + if (!kvm_trylock_all_vcpus(kvm)) { > + r = -EBUSY; > + goto out; > + } > + > + kvm_vm_dead(kvm); > + kvm_unlock_all_vcpus(kvm); > + > + __tdx_release_hkid(kvm, true); > +out: > + cpus_read_unlock(); > + return r; > +} > + > int tdx_vm_ioctl(struct kvm *kvm, void __user *argp) > { > struct kvm_tdx_cmd tdx_cmd; > @@ -2805,6 +2827,9 @@ int tdx_vm_ioctl(struct kvm *kvm, void __user *argp) > if (tdx_cmd.hw_error) > return -EINVAL; > > + if (tdx_cmd.id == KVM_TDX_TERMINATE_VM) > + return tdx_terminate_vm(kvm); > + > mutex_lock(&kvm->lock); > > switch (tdx_cmd.id) { > -- > 2.43.0 >