From patchwork Tue Mar 18 01:33:33 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yan Zhao X-Patchwork-Id: 14020148 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.9]) (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 9201D3FC2; Tue, 18 Mar 2025 01:34:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.9 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742261701; cv=none; b=su3voaj7lV/Tg757FBtgu831Sru5QzyuPy6xpu5Rfoz1cNUFHaCf9cyH8zsa3c4FhqYWhus5bNZbinNZtZnoDyq0yyNXoQYXtytDoNslfWbHXXxB+94RwERXJcyTvNtYDKxzUAy7L6q0rXhD3faU73q7TIkY7aw2thfm+0XibDk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742261701; c=relaxed/simple; bh=pLa7nmBIJgWzueqkPk4AGuMVC9d7jDDRLX/NlIBoDkQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=rR8dTBbhycszZCaw83CyIea1BYKJjq+5mOl0fANvEved1s9cKkgtbvCHyOkUi1izdy49LkE06M5g7tKdpZMWOx7S6FjlIXl6PQZPK0/Mz7uY0YtKtCTEL/TGwXvKT9ubM5ZuAE5PJb08tQkSmUlwRKVQs6GWOZc8vguu9zz7Br0= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=OvVBJbPJ; arc=none smtp.client-ip=192.198.163.9 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="OvVBJbPJ" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1742261699; x=1773797699; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=pLa7nmBIJgWzueqkPk4AGuMVC9d7jDDRLX/NlIBoDkQ=; b=OvVBJbPJkR/m4ylhBtL2MKFUzIzvhfoN0fqjRwqvXSwb9pe9LIp5BmPE j+uCrXLtKGg4CZPpJ3veK8ytqshoXxZuwywv7o94awrvQr0vOfYIUoIaz z3BVt8SAwj+c0WHXZaH9fb4DT+Npn/jU47z9FQu853rmPsexCUgC1TCTo Zit8fAbZvlaNUFZynDHLH+4DEwdL0374LSLDYOYRkkA9wRTaSLOwme6ZP ywGSa7VbYTrv3yg+4tXfhsn+Hn8neBoajIWLqfh+eb/8NhqedKD/2zlSU E1vzjboSggSA+k2ijgu1Wu8Y7TV0XMW68chqLCG12SzN6Pm4nePz0cUiw A==; X-CSE-ConnectionGUID: Opk93W7WQmq3+K/FC3CCBw== X-CSE-MsgGUID: xRFtpcyeQla3gHhonYOaow== X-IronPort-AV: E=McAfee;i="6700,10204,11376"; a="54009598" X-IronPort-AV: E=Sophos;i="6.14,255,1736841600"; d="scan'208";a="54009598" Received: from orviesa005.jf.intel.com ([10.64.159.145]) by fmvoesa103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Mar 2025 18:34:59 -0700 X-CSE-ConnectionGUID: P78im2mWSXK+g/BfK4CEXA== X-CSE-MsgGUID: MOrFEG6sR8iuttfa+EO9kA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.14,255,1736841600"; d="scan'208";a="127284151" Received: from yzhao56-desk.sh.intel.com ([10.239.159.62]) by orviesa005-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Mar 2025 18:34:57 -0700 From: Yan Zhao To: pbonzini@redhat.com, seanjc@google.com Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Yan Zhao Subject: [PATCH v2 5/5] KVM: x86/mmu: Check and free obsolete roots in kvm_mmu_reload() Date: Tue, 18 Mar 2025 09:33:33 +0800 Message-ID: <20250318013333.5817-1-yan.y.zhao@intel.com> X-Mailer: git-send-email 2.43.2 In-Reply-To: <20250318013038.5628-1-yan.y.zhao@intel.com> References: <20250318013038.5628-1-yan.y.zhao@intel.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Check request KVM_REQ_MMU_FREE_OBSOLETE_ROOTS to free obsolete roots in kvm_mmu_reload() to prevent kvm_mmu_reload() from seeing a stale obsolete root. Since kvm_mmu_reload() can be called outside the vcpu_enter_guest() path (e.g., kvm_arch_vcpu_pre_fault_memory()), it may be invoked after a root has been marked obsolete and before vcpu_enter_guest() is invoked to process KVM_REQ_MMU_FREE_OBSOLETE_ROOTS and set root.hpa to invalid. This causes kvm_mmu_reload() to fail to load a new root, which can lead to kvm_arch_vcpu_pre_fault_memory() being stuck in the while loop in kvm_tdp_map_page() since RET_PF_RETRY is always returned due to is_page_fault_stale(). Keep the existing check of KVM_REQ_MMU_FREE_OBSOLETE_ROOTS in vcpu_enter_guest() since the cost of kvm_check_request() is negligible, especially a check that's guarded by kvm_request_pending(). Export symbol of kvm_mmu_free_obsolete_roots() as kvm_mmu_reload() is inline and may be called outside of kvm.ko. Suggested-by: Sean Christopherson Signed-off-by: Yan Zhao --- arch/x86/kvm/mmu.h | 3 +++ arch/x86/kvm/mmu/mmu.c | 1 + 2 files changed, 4 insertions(+) diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h index 050a0e229a4d..f2b36d32ef40 100644 --- a/arch/x86/kvm/mmu.h +++ b/arch/x86/kvm/mmu.h @@ -104,6 +104,9 @@ void kvm_mmu_track_write(struct kvm_vcpu *vcpu, gpa_t gpa, const u8 *new, static inline int kvm_mmu_reload(struct kvm_vcpu *vcpu) { + if (kvm_check_request(KVM_REQ_MMU_FREE_OBSOLETE_ROOTS, vcpu)) + kvm_mmu_free_obsolete_roots(vcpu); + /* * Checking root.hpa is sufficient even when KVM has mirror root. * We can have either: diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 607cbb19ea96..15fd4838e4f2 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -5802,6 +5802,7 @@ void kvm_mmu_free_obsolete_roots(struct kvm_vcpu *vcpu) __kvm_mmu_free_obsolete_roots(vcpu->kvm, &vcpu->arch.root_mmu); __kvm_mmu_free_obsolete_roots(vcpu->kvm, &vcpu->arch.guest_mmu); } +EXPORT_SYMBOL_GPL(kvm_mmu_free_obsolete_roots); static u64 mmu_pte_write_fetch_gpte(struct kvm_vcpu *vcpu, gpa_t *gpa, int *bytes)