From patchwork Thu Nov 21 11:56:14 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yan Zhao X-Patchwork-Id: 13881952 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.15]) (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 9D91B1CB9E1; Thu, 21 Nov 2024 11:58:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.15 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732190339; cv=none; b=iv3XWPD/A5PcRoFY17/d0mR/3JQF3bW1Z5n7trLWyLWGY6oGK/KHVUKyFQc0BTYFbA8xpog0uvpCgHX1TLqq022P80sR1zDLCL2egDZkRQ/Vy6Q/g3sXZ5tsJSPTz+3PWgBf2LLKHA0LLj1RrwDdk3+ZA5iCMUFK9fdhXsQx0fk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732190339; c=relaxed/simple; bh=fWQidp6Vy8EzY8Z5MLIsw88ehF7LX69udiEoGr/XbgE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=E8HF0dqKq2tu00MOp+Tr/gRhxkNuPuESJWU3RLesYvsLH+hv5U2ITBI/HJv+t4gNLd9AHiV3O5ft7vph49it0t6HP/uIU8KPHFjD7HZEpcmLL1J3jSLBk7IBKZgfnTbDRzG0IofBRaf/KrjxWBUYQs8xWAG+T+bf6qWVWPBUYcI= 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=JeBwvqpV; arc=none smtp.client-ip=198.175.65.15 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="JeBwvqpV" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1732190337; x=1763726337; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=fWQidp6Vy8EzY8Z5MLIsw88ehF7LX69udiEoGr/XbgE=; b=JeBwvqpVWZkuJUqgU35FkPwxBtonaC+FJ/8T1AZTSSnLPK9TDSMsgfdX fJ1oPbkLB0IT8UUo0iw7AJwjjrr1tAh2XTDyBV9aIRq6DvhLU5WKjBtNW mJeGFzu8oX1AZ5Cr1U4jFyxtbdf3/H2QDXXg4BAK8vg+P7LbdzuFKP5x/ 1CvUUHjykAWWr7c7TUEcvoKbXz+UuKw+wbQHItu1G4JcIlbT0LECPWm2o 1V7TIEL7jSIGOoANCz4kOJLL1Gf+XAMRL3575DrmzZIm2tKK6q2vYNYvq 8NQLTgGNUecMy0ulUyYlXV0+FWgDr60NQzeCFZzshzuh9bThTpFBNvmj9 g==; X-CSE-ConnectionGUID: hnq9tm+4SUK02618TbDbww== X-CSE-MsgGUID: X9wV/npATiGTWudzG5zqEw== X-IronPort-AV: E=McAfee;i="6700,10204,11263"; a="35964894" X-IronPort-AV: E=Sophos;i="6.12,172,1728975600"; d="scan'208";a="35964894" Received: from orviesa006.jf.intel.com ([10.64.159.146]) by orvoesa107.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Nov 2024 03:58:57 -0800 X-CSE-ConnectionGUID: PgXNuszwTUmZbQ8uobpqqQ== X-CSE-MsgGUID: GdACVskXS76RhVcF7oPuow== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.12,172,1728975600"; d="scan'208";a="90354955" Received: from yzhao56-desk.sh.intel.com ([10.239.159.62]) by orviesa006-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Nov 2024 03:58:53 -0800 From: Yan Zhao To: pbonzini@redhat.com, seanjc@google.com, kvm@vger.kernel.org Cc: dave.hansen@linux.intel.com, rick.p.edgecombe@intel.com, kai.huang@intel.com, adrian.hunter@intel.com, reinette.chatre@intel.com, xiaoyao.li@intel.com, tony.lindgren@intel.com, binbin.wu@linux.intel.com, dmatlack@google.com, isaku.yamahata@intel.com, isaku.yamahata@gmail.com, nik.borisov@suse.com, linux-kernel@vger.kernel.org, x86@kernel.org, Yan Zhao Subject: [RFC PATCH 1/2] KVM: TDX: Retry in TDX when installing TD private/sept pages Date: Thu, 21 Nov 2024 19:56:14 +0800 Message-ID: <20241121115614.26363-1-yan.y.zhao@intel.com> X-Mailer: git-send-email 2.43.2 In-Reply-To: <20241121115139.26338-1-yan.y.zhao@intel.com> References: <20241121115139.26338-1-yan.y.zhao@intel.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 For tdh_mem_page_add, Just return error when TDX_OPERAND_BUSY is found. For tdh_mem_sept_add(), tdh_mem_page_aug(), - Return -EBUSY in KVM for TDX_OPERAND_BUSY to cause RET_PF_RETRY to be returned in kvm_mmu_do_page_fault()/kvm_mmu_page_fault(). - Inside TDX's EPT violation handler, retry on RET_PF_RETRY as long as there are no pending signals/interrupts. Signed-off-by: Yan Zhao --- arch/x86/kvm/mmu/mmu.c | 2 +- arch/x86/kvm/vmx/tdx.c | 53 +++++++++++++++++++++++++++++++++++------- 2 files changed, 45 insertions(+), 10 deletions(-) diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index bd2eaa1dbebb..f16c0e7248eb 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -6179,7 +6179,7 @@ int noinline kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, u64 err vcpu->stat.pf_spurious++; if (r != RET_PF_EMULATE) - return 1; + return r; emulate: return x86_emulate_instruction(vcpu, cr2_or_gpa, emulation_type, insn, diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c index 23e6f25dd837..60d9e9d050ad 100644 --- a/arch/x86/kvm/vmx/tdx.c +++ b/arch/x86/kvm/vmx/tdx.c @@ -1705,8 +1705,9 @@ int tdx_sept_link_private_spt(struct kvm *kvm, gfn_t gfn, err = tdh_mem_sept_add(to_kvm_tdx(kvm)->tdr_pa, gpa, tdx_level, hpa, &entry, &level_state); - if (unlikely(err == TDX_ERROR_SEPT_BUSY)) - return -EAGAIN; + if (unlikely(err & TDX_OPERAND_BUSY)) + return -EBUSY; + if (KVM_BUG_ON(err, kvm)) { pr_tdx_error_2(TDH_MEM_SEPT_ADD, err, entry, level_state); return -EIO; @@ -1855,6 +1856,8 @@ static int tdx_handle_ept_violation(struct kvm_vcpu *vcpu) { gpa_t gpa = tdexit_gpa(vcpu); unsigned long exit_qual; + bool local_retry = false; + int ret; if (vt_is_tdx_private_gpa(vcpu->kvm, gpa)) { if (tdx_is_sept_violation_unexpected_pending(vcpu)) { @@ -1873,6 +1876,23 @@ static int tdx_handle_ept_violation(struct kvm_vcpu *vcpu) * due to aliasing a single HPA to multiple GPAs. */ exit_qual = EPT_VIOLATION_ACC_WRITE; + + /* + * Mapping of private memory may meet RET_PF_RETRY due to + * SEAMCALL contentions, e.g. + * - TDH.MEM.PAGE.AUG/TDH.MEM.SEPT.ADD on local vCPU vs + * TDH.VP.ENTER with 0-step mitigation on a remote vCPU. + * - TDH.MEM.PAGE.AUG/TDH.MEM.SEPT.ADD on local vCPU vs + * TDG.MEM.PAGE.ACCEPT on a remote vCPU. + * + * Retry internally in TDX to prevent exacerbating the + * activation of 0-step mitigation on local vCPU. + * However, despite these retries, the 0-step mitigation on the + * local vCPU may still be triggered due to: + * - Exiting on signals, interrupts. + * - KVM_EXIT_MEMORY_FAULT. + */ + local_retry = true; } else { exit_qual = tdexit_exit_qual(vcpu); /* @@ -1885,7 +1905,24 @@ static int tdx_handle_ept_violation(struct kvm_vcpu *vcpu) } trace_kvm_page_fault(vcpu, tdexit_gpa(vcpu), exit_qual); - return __vmx_handle_ept_violation(vcpu, tdexit_gpa(vcpu), exit_qual); + + while (1) { + ret = __vmx_handle_ept_violation(vcpu, gpa, exit_qual); + + if (ret != RET_PF_RETRY || !local_retry) + break; + + /* + * Break and keep the orig return value. + * Signal & irq handling will be done later in vcpu_run() + */ + if (signal_pending(current) || pi_has_pending_interrupt(vcpu) || + kvm_test_request(KVM_REQ_NMI, vcpu) || vcpu->arch.nmi_pending) + break; + + cond_resched(); + } + return ret; } int tdx_handle_exit(struct kvm_vcpu *vcpu, fastpath_t fastpath) @@ -3028,13 +3065,11 @@ static int tdx_gmem_post_populate(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn, } ret = 0; - do { - err = tdh_mem_page_add(kvm_tdx->tdr_pa, gpa, pfn_to_hpa(pfn), - pfn_to_hpa(page_to_pfn(page)), - &entry, &level_state); - } while (err == TDX_ERROR_SEPT_BUSY); + err = tdh_mem_page_add(kvm_tdx->tdr_pa, gpa, pfn_to_hpa(pfn), + pfn_to_hpa(page_to_pfn(page)), + &entry, &level_state); if (err) { - ret = -EIO; + ret = unlikely(err & TDX_OPERAND_BUSY) ? -EBUSY : -EIO; goto out; }