From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 088D5606A33B for ; Wed, 28 Oct 2026 19:03:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=lists.infradead.org header.i=@lists.infradead.org header.a=rsa-sha256 header.s=bombadil.20210309 header.b=PA1PDeFE; dkim=pass (2048-bit key, unprotected) header.d=google.com header.i=@google.com header.a=rsa-sha256 header.s=20260707 header.b=HFA2Yfl0 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:Reply-To:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Type:Cc:To: From:Subject:Message-ID:Mime-Version:Date:Content-Transfer-Encoding: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References: List-Unsubscribe-Post:List-Owner; bh=HbuVr5an123e2WdNsh7qTkraPx2QUzUAuDpOvbvX5g4=; b=PA1PDeFEn6m1xQVIt5f6noVYA2 1rW39Q08INGGCNTapivQbLKyeBWF70m8ABs0qp3rAnHYGh71VmCyJSWN25MnzkweMWMpN3aR3vTtS riNMBC0gWXI8rVOPJHF/mXDstZ7/3TuTYzpkC9jbtypx6Qfhd8iKLSYDAwsjXfhjE725kLYrZZ1je ObjT8EzxUlEYYp8rxFwHuUK12jBAolA8E+JlicBwFr8euM1zR7boKyv0cXShNMSqKnbkrxKqcePbZ VfCfDoZgfOtJSKI7srb2oGDkVfShccICiEwHDZ6aUgFYULgFFfdxdUpwUdRgHF+s6vX2qvxXP+SbX drJO7MEA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.100.1 #2 (Red Hat Linux)) id 1xM8vS-00000007nS7-0paG; Wed, 28 Oct 2026 19:03:06 +0000 Received: from mail-pf1-x446.google.com ([2607:f8b0:4864:20::446]) by bombadil.infradead.org with esmtps (Exim 4.100.1 #2 (Red Hat Linux)) id 1xM8vP-00000007nQ6-3Pds for linux-arm-kernel@lists.infradead.org; Wed, 28 Oct 2026 19:03:05 +0000 Received: by mail-pf1-x446.google.com with SMTP id d2e1a72fcca58-8a064f294cbso916192b3a.2 for ; Wed, 28 Oct 2026 12:03:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20260707; t=1793214182; x=1793818982; darn=lists.infradead.org; h=content-type:cc:to:from:subject:message-id:mime-version:date :reply-to:from:to:cc:subject:date:message-id:reply-to:content-type; bh=HbuVr5an123e2WdNsh7qTkraPx2QUzUAuDpOvbvX5g4=; b=HFA2Yfl0qTJoOMyX1RF+lgP0cNFt0v3VklrJBm/bwhrhtGoif54eXqiLCyZbqdYjUJ wDbRXgK4m/EPZ+bVpVihufgVinKMNCJkP7prjsRFuWB33BJhASxOPPy7hePY+dAgTQk7 igoULsaOSHbmXeJN+hB2Vx23++Igt9cxhK+2unp9yj+YuO6uU6xef38YIE+stZd6Sms6 RBin0/vCt2kh3IEwv97vOB4FqjW7FJXqlJ94H/55tI8zQBTVHnUtu/SpWoX8EIo4kuI0 lLAz8uMDJkwCCZe4oI/lIYnsKpgY1a3NQ9NcGHHlsaIROSaxvFwDylfnEvFBavdcTKSj 8E4w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1793214182; x=1793818982; h=content-type:cc:to:from:subject:message-id:mime-version:date :reply-to:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to:content-type; bh=HbuVr5an123e2WdNsh7qTkraPx2QUzUAuDpOvbvX5g4=; b=WUEiuUMs6J1eLGRmL9zVwWu8C6Dwf9j4XjcSJ3W9pDDyf0aKnp5MpQAPa07R8afISC CQdaQi46Eo2TnZCVekILdqGsftxZVi2CUa4iwRfdjfYnh5NJDFF2FCCCOn8m5HKwnSx4 TAsN/DnBpqIfaP2o4ki1OPBsX/UAt4nVJzVgdvl9aAKh/KUASt0w+i1IW7p6+USrIFne dUS1SFORpi8UFOqapWfKb2DVLrBYLVwjaZUUs183g0G/czA7QuMPM6EBiRVQ0dc3IfaZ kRRrs6aebuiu+zHTbknInXyZ3uMBv8vaAUdKj38bUhOd39tZBg+p+O+oCOA/II/Q8+W4 2SHA== X-Forwarded-Encrypted: i=1; AKwUvBwvGLFlhrg5isuxgU9405QfH1UMVibsL3INaJ1y8dOULJeoh9A/5WN/al80Kpz3kpcL38L2jkeva2++EHJoCLyc@lists.infradead.org X-Gm-Message-State: AFq9FYJDy7l9+nXuRrmV0l7ozQLPjTjLNu7XYNFslqLSMHW5qkEEcV9F SL9AVXxPZVdB4hMfW35QpuFdyqUVw6Up6Ceh+5t+4v/rPG+KEGV7ezUz6MD8Swnc70muqjHpY7/ QCH4v7g== X-Received: from pfog22.prod.google.com ([2002:aa7:8756:0:b0:8a0:7e84:9992]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a00:18a8:b0:899:55e9:880b with SMTP id d2e1a72fcca58-8a6e72dc7admr2727923b3a.14.1793214181492; Wed, 28 Oct 2026 12:03:01 -0700 (PDT) Date: Wed, 28 Oct 2026 12:02:52 -0700 X-Archived-By: Mime-Version: 1.0 X-Mailer: git-send-email 2.56.0.313.g2479322e68-goog Message-ID: <20261028190259.1819571-1-seanjc@google.com> Subject: [PATCH 0/7] KVM: Ensure WAIT requests actually wait From: Sean Christopherson To: Marc Zyngier , Oliver Upton , Tianrui Zhao , Bibo Mao , Huacai Chen , Madhavan Srinivasan , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Sean Christopherson , Paolo Bonzini Cc: Fuad Tabba , Joey Gouly , Steffen Eiden , Suzuki K Poulose , Zenghui Yu , Nicholas Piggin , Atish Patra , Alexandre Ghiti , 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, linux-kernel@vger.kernel.org, Stefan Teodorescu Content-Type: text/plain; charset="UTF-8" X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20261028_120303_854120_F32043B5 X-CRM114-Status: GOOD ( 10.71 ) X-Spam-Score: -9.5 (---------) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Sean Christopherson Sender: "linux-arm-kernel" X-Spam-Status: No, score=-21.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIMWL_WL_MED,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT,USER_IN_DEF_DKIM_WL autolearn=unavailable autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 Fix a bug in where kvm_make_request_and_kick() won't actually wait if the kick races without another non-waiting kick. The issue is that all of the conditional kvm_arch_vcpu_should_kick() implementations are missing this code: if (req & KVM_REQUEST_WAIT) return mode != OUTSIDE_GUEST_MODE; Thankfully, kvm_request_needs_ipi() does the right thing, so this doesn't affect kvm_make_all_cpus_request() or kvm_make_vcpus_request_mask(), i.e. it's limited to x86 SNP's used of kvm_make_request_and_kick(). To fix, address this TODO: /* TODO: merge with kvm_arch_vcpu_should_kick */ and purge kvm_arch_vcpu_should_kick(). As usual, PPC makes that difficult because it has wonky code that is poorly documented. For reasons unknown, kvm_vcpu_kick() unconditionally returns true on (most flavors of) PPC. To preserve that behavior, add a compatibility wrapper in PPC, along with a @force param to __kvm_vcpu_kick(). This series would ideally go into 7.4, even though it's obviously not small, as guest_memfd in-place conversion massively widens the window where a missed kick+wait can lead to the host trying to reclaim an in-use VMSA page, which is generally fatal to the host. Sean Christopherson (7): KVM: s390: Drop unused and unreachable kvm_arch_vcpu_should_kick() KVM: Add a @force param to __kvm_vcpu_kick() for PPC backwards compatibility KVM: PPC: Explicitly force IPIs when directly kicking vCPUs KVM: MIPS: Rework kvm_arch_vcpu_should_kick() to use standard implementation KVM: Move kvm_arch_vcpu_should_kick() to common code as kvm_vcpu_should_kick() KVM: Plumb the full request into __kvm_vcpu_kick() KVM: Drop kvm_vcpu_should_kick() and use kvm_request_needs_ipi() arch/arm64/kvm/arm.c | 5 ----- arch/loongarch/kvm/vcpu.c | 5 ----- arch/mips/kvm/mips.c | 5 ----- arch/powerpc/include/asm/kvm_ppc.h | 13 ++++++++++++- arch/powerpc/kvm/book3s.c | 4 ++-- arch/powerpc/kvm/book3s_pr.c | 2 +- arch/powerpc/kvm/booke.c | 6 +++--- arch/powerpc/kvm/e500_emulate.c | 2 +- arch/powerpc/kvm/powerpc.c | 7 +------ arch/riscv/kvm/vcpu.c | 5 ----- arch/s390/kvm/s390/s390.c | 7 ------- arch/x86/kvm/x86.c | 5 ----- include/linux/kvm_host.h | 7 +++---- virt/kvm/kvm_main.c | 28 ++++++++++++++++------------ 14 files changed, 39 insertions(+), 62 deletions(-) base-commit: 7e60162b16f9da0d2fa83da5c1723b6853a0ac1d -- 2.56.0.313.g2479322e68-goog