From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pj1-f74.google.com (mail-pj1-f74.google.com [209.85.216.74]) (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 A0E87329E7B for ; Thu, 30 Oct 2025 20:10:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.74 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761855055; cv=none; b=HNWPJmNEqfQCPhrPaUL6SV47rYscy8ntbTGoat8AGqbPEPsuUDl5+25UQEzLN/ZpawKwT8kkWXXKKdIg35dVQgE6JGhk7SQgXD2/lxcML+Vrs71tQAe2cYMBPjiySZiy7NTZsCmirdhpIRT2D6Rq/zAPnssoMzHjrYcOuVTTVmQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761855055; c=relaxed/simple; bh=1TeuJjhP9mqGMQJvgPXRft34enFs+P5PX2+/Rfvv+AU=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=WuSyX3uYzUA4kJLi95XUclf1crH+rcs44qFdjmduzDctCktszMZ2aN1UjKDLPvnC8Ae0HdCwBAVm1RzxxF93vgpX/wjLZtmcaJqknau5UKakUj2iqt/T9fLMv9zNxZ5BxSfrfuodBYoB2JTVmKEnY97Rk3VDbxTEQJtUyE/D1Q4= 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=swbw04gt; arc=none smtp.client-ip=209.85.216.74 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="swbw04gt" Received: by mail-pj1-f74.google.com with SMTP id 98e67ed59e1d1-33da1f30fdfso3305159a91.3 for ; Thu, 30 Oct 2025 13:10:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1761855052; x=1762459852; darn=lists.linux.dev; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:from:to:cc:subject:date:message-id:reply-to; bh=xpa5Fver89jqQUHMNWla6MmRTI/zYJOh/l7CEBc/74M=; b=swbw04gt4zInqtyCM//rstsxed1+FbrDoKjgCHLZyHdC2l3sKNn8HvCO622l811qEc IYY3nKIwA3oSDxAsDkyfs2BR6o3yR89noX6d3xpyek+jGx+qhCzyGkI1abpSLYFIe5xj bArByV/GPC4w2JmCpfqTxaK6oWc2GG8zrnDx0VJkfEt4f1mZsBODr0mY6jUtOhJJ5VH/ 3Ru+Cvmx0CUVhzjJ1WsqR6nyH6DN1MhpyVFuxoRN4tF8wTXSXS+U1JouPVOo5diOn2pG 9ynRnm2NQTFmbFsIgdFSTPqcBvEtwedPmbGhCC+SNB4LyrgaXUktgAXAEPXRYP8Pt+X0 xg6w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1761855052; x=1762459852; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=xpa5Fver89jqQUHMNWla6MmRTI/zYJOh/l7CEBc/74M=; b=fvxUsykJF73XPswozpCLMSJjv7XB/VWdcGP/+jc3ppiTd0G+wCCEgk4XVdmHeas29S R38+7rJRY/kseKG3PPw6DS08UmINnZPiuZpR+xBw3fSzKhkONfX1HnVBckk2qGmXw02I mehifvkamQWHrencqBwFr/cIL6UUajqJCzmYeMfScu3EiE6yYCynE3ST9+B6QJetKsQp hUXE/z/VSp8paQi3ngUIddg0dQL3KKa4RGSsxJ4G3hWD2P2F7I4hQC33tyYehYVCOPaP AIUGZrVxxP+RAbgrEhouTCYyspbUAwMH/wJiyb1M3hDOIyFstFY+KlqKrxR23fEhflE3 AvfQ== X-Forwarded-Encrypted: i=1; AJvYcCXdmtbXlk9ADc9n/9v3lRycmFRaOqD0EVYmSiea+EIcb4vu2vP8tEYFwNDZCmCbaQs6ElND59M=@lists.linux.dev X-Gm-Message-State: AOJu0YyIfIYFLZN91iuZ4JS0azDUPd1bTQw11JxSv83dTNwYxZvhUBcT 4X1/MZjNH2oIldg42/jW1EPmSlHOHxGjaiYtOkahDM1I0Qa7Z77Qpl78t1Jl6KHn6eYDgVgrB2s XUdwEyg== X-Google-Smtp-Source: AGHT+IGdH9ACR3MS+ju/IeUipjD96kAUXZo3BjKEOn1spE0qh/NlJMuCLno+Rlt479ILTGbPCBlzBUGVIBM= X-Received: from pjl4.prod.google.com ([2002:a17:90b:2f84:b0:339:dc19:ae60]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90b:3c52:b0:338:3789:2e7b with SMTP id 98e67ed59e1d1-34082fd9099mr1370626a91.13.1761855052135; Thu, 30 Oct 2025 13:10:52 -0700 (PDT) Reply-To: Sean Christopherson Date: Thu, 30 Oct 2025 13:09:44 -0700 In-Reply-To: <20251030200951.3402865-1-seanjc@google.com> Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20251030200951.3402865-1-seanjc@google.com> X-Mailer: git-send-email 2.51.1.930.gacf6e81ea2-goog Message-ID: <20251030200951.3402865-22-seanjc@google.com> Subject: [PATCH v4 21/28] KVM: TDX: Add macro to retry SEAMCALLs when forcing vCPUs out of guest From: Sean Christopherson To: Marc Zyngier , Oliver Upton , Tianrui Zhao , Bibo Mao , Huacai Chen , Madhavan Srinivasan , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Sean Christopherson , Paolo Bonzini , "Kirill A. Shutemov" Cc: linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, kvm@vger.kernel.org, loongarch@lists.linux.dev, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, x86@kernel.org, linux-coco@lists.linux.dev, linux-kernel@vger.kernel.org, Ira Weiny , Kai Huang , Binbin Wu , Michael Roth , Yan Zhao , Vishal Annapurve , Rick Edgecombe , Ackerley Tng Content-Type: text/plain; charset="UTF-8" Add a macro to handle kicking vCPUs out of the guest and retrying SEAMCALLs on -EBUSY instead of providing small helpers to be used by each SEAMCALL. Wrapping the SEAMCALLs in a macro makes it a little harder to tease out which SEAMCALL is being made, but significantly reduces the amount of copy+paste code and makes it all but impossible to leave an elevated wait_for_sept_zap. Signed-off-by: Sean Christopherson --- arch/x86/kvm/vmx/tdx.c | 82 +++++++++++++++++------------------------- 1 file changed, 33 insertions(+), 49 deletions(-) diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c index 999b519494e9..97632fc6b520 100644 --- a/arch/x86/kvm/vmx/tdx.c +++ b/arch/x86/kvm/vmx/tdx.c @@ -294,25 +294,34 @@ static inline void tdx_disassociate_vp(struct kvm_vcpu *vcpu) vcpu->cpu = -1; } -static void tdx_no_vcpus_enter_start(struct kvm *kvm) -{ - struct kvm_tdx *kvm_tdx = to_kvm_tdx(kvm); - - lockdep_assert_held_write(&kvm->mmu_lock); - - WRITE_ONCE(kvm_tdx->wait_for_sept_zap, true); - - kvm_make_all_cpus_request(kvm, KVM_REQ_OUTSIDE_GUEST_MODE); -} - -static void tdx_no_vcpus_enter_stop(struct kvm *kvm) -{ - struct kvm_tdx *kvm_tdx = to_kvm_tdx(kvm); - - lockdep_assert_held_write(&kvm->mmu_lock); - - WRITE_ONCE(kvm_tdx->wait_for_sept_zap, false); -} +/* + * Execute a SEAMCALL related to removing/blocking S-EPT entries, with a single + * retry (if necessary) after forcing vCPUs to exit and wait for the operation + * to complete. All flows that remove/block S-EPT entries run with mmu_lock + * held for write, i.e. are mutually exclusive with each other, but they aren't + * mutually exclusive with running vCPUs, and so can fail with "operand busy" + * if a vCPU acquires a relevant lock in the TDX-Module, e.g. when doing TDCALL. + * + * Note, the retry is guaranteed to succeed, absent KVM and/or TDX-Module bugs. + */ +#define tdh_do_no_vcpus(tdh_func, kvm, args...) \ +({ \ + struct kvm_tdx *__kvm_tdx = to_kvm_tdx(kvm); \ + u64 __err; \ + \ + lockdep_assert_held_write(&kvm->mmu_lock); \ + \ + __err = tdh_func(args); \ + if (unlikely(tdx_operand_busy(__err))) { \ + WRITE_ONCE(__kvm_tdx->wait_for_sept_zap, true); \ + kvm_make_all_cpus_request(kvm, KVM_REQ_OUTSIDE_GUEST_MODE); \ + \ + __err = tdh_func(args); \ + \ + WRITE_ONCE(__kvm_tdx->wait_for_sept_zap, false); \ + } \ + __err; \ +}) /* TDH.PHYMEM.PAGE.RECLAIM is allowed only when destroying the TD. */ static int __tdx_reclaim_page(struct page *page) @@ -1722,14 +1731,7 @@ static void tdx_track(struct kvm *kvm) */ lockdep_assert_held_write(&kvm->mmu_lock); - err = tdh_mem_track(&kvm_tdx->td); - if (unlikely(tdx_operand_busy(err))) { - /* After no vCPUs enter, the second retry is expected to succeed */ - tdx_no_vcpus_enter_start(kvm); - err = tdh_mem_track(&kvm_tdx->td); - tdx_no_vcpus_enter_stop(kvm); - } - + err = tdh_do_no_vcpus(tdh_mem_track, kvm, &kvm_tdx->td); TDX_BUG_ON(err, TDH_MEM_TRACK, kvm); kvm_make_all_cpus_request(kvm, KVM_REQ_OUTSIDE_GUEST_MODE); @@ -1781,14 +1783,8 @@ static void tdx_sept_remove_private_spte(struct kvm *kvm, gfn_t gfn, if (KVM_BUG_ON(level != PG_LEVEL_4K, kvm)) return; - err = tdh_mem_range_block(&kvm_tdx->td, gpa, tdx_level, &entry, &level_state); - if (unlikely(tdx_operand_busy(err))) { - /* After no vCPUs enter, the second retry is expected to succeed */ - tdx_no_vcpus_enter_start(kvm); - err = tdh_mem_range_block(&kvm_tdx->td, gpa, tdx_level, &entry, &level_state); - tdx_no_vcpus_enter_stop(kvm); - } - + err = tdh_do_no_vcpus(tdh_mem_range_block, kvm, &kvm_tdx->td, gpa, + tdx_level, &entry, &level_state); if (TDX_BUG_ON_2(err, TDH_MEM_RANGE_BLOCK, entry, level_state, kvm)) return; @@ -1803,20 +1799,8 @@ static void tdx_sept_remove_private_spte(struct kvm *kvm, gfn_t gfn, * with other vcpu sept operation. * Race with TDH.VP.ENTER due to (0-step mitigation) and Guest TDCALLs. */ - err = tdh_mem_page_remove(&kvm_tdx->td, gpa, tdx_level, &entry, - &level_state); - - if (unlikely(tdx_operand_busy(err))) { - /* - * The second retry is expected to succeed after kicking off all - * other vCPUs and prevent them from invoking TDH.VP.ENTER. - */ - tdx_no_vcpus_enter_start(kvm); - err = tdh_mem_page_remove(&kvm_tdx->td, gpa, tdx_level, &entry, - &level_state); - tdx_no_vcpus_enter_stop(kvm); - } - + err = tdh_do_no_vcpus(tdh_mem_page_remove, kvm, &kvm_tdx->td, gpa, + tdx_level, &entry, &level_state); if (TDX_BUG_ON_2(err, TDH_MEM_PAGE_REMOVE, entry, level_state, kvm)) return; -- 2.51.1.930.gacf6e81ea2-goog