From nobody Mon Feb 9 12:15:44 2026 Received: from mail-pl1-f202.google.com (mail-pl1-f202.google.com [209.85.214.202]) (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 A003920330 for ; Sat, 1 Feb 2025 01:14:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.202 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738372449; cv=none; b=mHSjYjCR0MNrTgSRtlF5ynk5kJrjYUrgV3fiXDZJJIgKqBSdnwv0vNNIEm4QdmKeNB+NndqL+9eJzDvIIOcyOXuQw0IlR0OFMU4YiSj1iugPizv9twFxVX0gwdCnxMlwAsEjTTUUTVfenOZw1HVMRW+aDO1kViTcnMi1ZobdseE= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738372449; c=relaxed/simple; bh=Tg8GhNLpPA34vQJNweaMVYaIAHTcnBOATqkxrRePjzk=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=Rp+wrZ52HbaKFOQzBBMxQaZ4OWe3kInX1EAmUh6PuK4Vb+scLUNp9V5DqHBs0n4cnDhelt+eSTp0ULmXXgfFkGA02y+a1/LGjR2W4mePYhJmMk48Gm36pK0jNxYpdqgNlLPTtgnJ5ZLupcCGcAVpVLkYhgqqaUUNDoWhNyTlnkw= 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=lmLuxJA4; arc=none smtp.client-ip=209.85.214.202 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="lmLuxJA4" Received: by mail-pl1-f202.google.com with SMTP id d9443c01a7336-216387ddda8so54658155ad.3 for ; Fri, 31 Jan 2025 17:14:07 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1738372447; x=1738977247; darn=vger.kernel.org; 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=8BJ4lYogToOhLZ7GzltFe2z01ZGXRRujJHAawRGlx94=; b=lmLuxJA4T+03nwub+046KPHLq8suX77ujRsOzsS7TQeDMEossCYNNtJh76lPdkR5cn bjiOFuyY299Q7+OWDjBKxkhWc0ah54ftu9s/U6rqxMcoQs2+48bTg/VJXwp6CCxhdb59 KsGUtr8bG1t2xQyhnNRxQ8f+SLThnSSbf5zQYMcVmWKZ+51HQpyxkYziDyLOoMyto8uG E7SMTbmREK8QAuIPC6w/kuNLtRcUVSxYMvOpCCyDC+51vO5XJ7rlsuQD1xz9fV6zzjrC wZ9+cJ9fX/LYadqf86+7RD38vgdWMvOlpO0MDylXsXykpV5HVfVAENakcXMkvFdq2+CK gqag== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1738372447; x=1738977247; 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=8BJ4lYogToOhLZ7GzltFe2z01ZGXRRujJHAawRGlx94=; b=f+Z6MndgcNIDo2kS6xaYiYpmlgjsbx80HtqvanfvKOcyl+uMdjpNZR+62/aP2KkYYC 6FP079Bz6kc3xa94JKP98e3gOwLeogndEoDYPBNLFzbdsJmFfDuY+S/Gw0Tbf/tV6hX0 xU3uNqvshU4L7iayP8vMewJ9fk1S43pKqB+IFRijD1U2R+xeLt+lJcXJ4nOPWLMIbyPD 1SV4qZlYmJRkd7Zpt880uRPZ3wN+iGaatecs1KGHQEMRmMzCPQEvoIegNHgocKk+tzSD gOHWcXkF3rP0xC92qKtUwaRD+aX8EwTOsBtdYY+dqH9+0cqSnhkklN2/y/hkSJn1isoS 4Hxg== X-Forwarded-Encrypted: i=1; AJvYcCXKjmpL8HAKx0Ln0Qb5LTs0HveEKwuPMLo1uR2WCI5qqxK/93W0NZAF6s9UQUS4VOL90Xb7cWsr5MvrTVU=@vger.kernel.org X-Gm-Message-State: AOJu0YyIyiBTLHRh/bEAC8wYKT/trcs18nRUvZOrhie3ltDFPP6n6I3G gmkKvNDPm24v5EvOMdom2wWBJzmxqxJ+tk37dkz/cB4Z6irI2PP2Pn9cUfXIhbc+3p7F8J4YkC7 pRQ== X-Google-Smtp-Source: AGHT+IHtd/xn8X4/ZTBhWNwmLHwRcrXbBlCFmDpoSEG9bkywbg9XeRZ2Td6Ob3lUwcyyzNaiLUtTD89OvYA= X-Received: from pgjz10.prod.google.com ([2002:a63:e54a:0:b0:7fd:50ab:dc45]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a20:7343:b0:1e1:ab8b:dda1 with SMTP id adf61e73a8af0-1ed7a6e0999mr25109821637.35.1738372446922; Fri, 31 Jan 2025 17:14:06 -0800 (PST) Reply-To: Sean Christopherson Date: Fri, 31 Jan 2025 17:13:57 -0800 In-Reply-To: <20250201011400.669483-1-seanjc@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250201011400.669483-1-seanjc@google.com> X-Mailer: git-send-email 2.48.1.362.g079036d154-goog Message-ID: <20250201011400.669483-3-seanjc@google.com> Subject: [PATCH 2/5] KVM: x86/xen: Add an #ifdef'd helper to detect writes to Xen MSR From: Sean Christopherson To: Sean Christopherson , Paolo Bonzini , David Woodhouse , Paul Durrant Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, syzbot+cdeaeec70992eca2d920@syzkaller.appspotmail.com, Joao Martins , David Woodhouse Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Add a helper to detect writes to the Xen hypercall page MSR, and provide a stub for CONFIG_KVM_XEN=3Dn to optimize out the check for kernels built without Xen support. Signed-off-by: Sean Christopherson Reviewed-by: David Woodhouse Reviewed-by: Paul Durrant --- arch/x86/kvm/x86.c | 2 +- arch/x86/kvm/xen.h | 10 ++++++++++ 2 files changed, 11 insertions(+), 1 deletion(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index b2d9a16fd4d3..f13d9d3f7c60 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3733,7 +3733,7 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct = msr_data *msr_info) u32 msr =3D msr_info->index; u64 data =3D msr_info->data; =20 - if (msr && msr =3D=3D vcpu->kvm->arch.xen_hvm_config.msr) + if (kvm_xen_is_hypercall_page_msr(vcpu->kvm, msr)) return kvm_xen_write_hypercall_page(vcpu, data); =20 switch (msr) { diff --git a/arch/x86/kvm/xen.h b/arch/x86/kvm/xen.h index f5841d9000ae..e92e06926f76 100644 --- a/arch/x86/kvm/xen.h +++ b/arch/x86/kvm/xen.h @@ -56,6 +56,11 @@ static inline bool kvm_xen_msr_enabled(struct kvm *kvm) kvm->arch.xen_hvm_config.msr; } =20 +static inline bool kvm_xen_is_hypercall_page_msr(struct kvm *kvm, u32 msr) +{ + return msr && msr =3D=3D kvm->arch.xen_hvm_config.msr; +} + static inline bool kvm_xen_hypercall_enabled(struct kvm *kvm) { return static_branch_unlikely(&kvm_xen_enabled.key) && @@ -124,6 +129,11 @@ static inline bool kvm_xen_msr_enabled(struct kvm *kvm) return false; } =20 +static inline bool kvm_xen_is_hypercall_page_msr(struct kvm *kvm, u32 msr) +{ + return false; +} + static inline bool kvm_xen_hypercall_enabled(struct kvm *kvm) { return false; --=20 2.48.1.362.g079036d154-goog