From nobody Thu Oct 2 03:32:41 2025 Received: from mail-pg1-f202.google.com (mail-pg1-f202.google.com [209.85.215.202]) (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 D03C6263F44 for ; Tue, 23 Sep 2025 15:37:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.215.202 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758641868; cv=none; b=k2s4QeuOo9yeNyBxoLNgrTMxisTHrx+otD4PxEh/9yInbjwJcVYk2KRakx1RnBWhj32TZatU8nNf3d5FlFBFQ+iQ1O58DD19A5Rd/wPhx7NuZzxdumkNJC/jLk9lo6iJAnVcD6AXmy1OcCGLAaGX422Nn/PAiBdq8CvSNlvZE/Y= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758641868; c=relaxed/simple; bh=4swEKEjr9ZfU+UhcssFhlBXgoat9+0rZuV4f1sVbGQk=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=ZbXJ16LiK+vegIf2u0DcRRV/ZmW8onjwk48imDh59GAHB7ukpgVrmGeXCziNvvrbbxg2KTcgOAHJAqhwmsJkWQ01ESCqSOlDuzp4scrVmj5R1UI3Y03uLgLgLiFOrktNSfCFZWLQT5OQJ5TVkxAh45fUy/X4QYV00OiCpWrpcqU= 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=AHJUA1vr; arc=none smtp.client-ip=209.85.215.202 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="AHJUA1vr" Received: by mail-pg1-f202.google.com with SMTP id 41be03b00d2f7-b54df707c1cso3486795a12.2 for ; Tue, 23 Sep 2025 08:37:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1758641866; x=1759246666; 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=RPQBXX/kV1DT6qccrRylEa2l6eEjE9QWLJ5e48WHMIs=; b=AHJUA1vrowf9iGV/k69rs8bWenM5WVB/6ero/JywlrgUES2exNT6+QZwldL3BvlTRg 9/nbI9k79EkZbdd83irH3kV+unZHYmo+rbOrPf2iyqgjPjvgNVK979JRGs9Bf85Q6oe5 pqp/DrZx1cBa/vWs5SUOCToh69SVbClFB9i5BADXhYipMbsO0hgJ/dt/eTognteqN5CM ikM6wpnkEFuz/cdOSNg1oBZ8aTGeYej80vo9OFvwRfEOkKmKSOScTXFW8qg0DI27+QtW 7S1Kdc9Hi14bqDCml/+vNWqb8r8DGhI+eiAiebd5D4IKtmJyf/3gLdgsG764yJagLs+M ogGA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1758641866; x=1759246666; 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=RPQBXX/kV1DT6qccrRylEa2l6eEjE9QWLJ5e48WHMIs=; b=Gb1kpDmf6691z8Od4Nml2QnJaRMHmeCnGhZ0JOcgcorjlxVI2Xb5EqTRyrkOUBk8I7 btyx98SDYf1GpHJMy3dSCu1ScbbEGJi0fruKMXV6oBOxq9QfQb6wYt9VIXLSfz+5OI2+ UmhGGqy3NhkxMtQYqIkt50lY29R3QBkQk7mrJvw5wv1uH5nPd7SbTky1YF0eNYUtQVRL NUYxCnjx5ppAQE4pFrzRBuNSE0Un3GmD2HRTVk4E5YNmYyZ2GOBlp134eeL4Jrx0OWoI jFoHfzHxhPiuOwWkW8HVPoAcwC6UpGjs6IkjMPZan28MVgIzyFkROhEU9CoNDkEjoTMA szDw== X-Forwarded-Encrypted: i=1; AJvYcCWfk8dVmOynwolUGkswz8SUbh0GI8l5PtiZesfJHC0pGMb/PgBXYe84YygFqzYRBTBHEjmdb6Dv0J2xPoQ=@vger.kernel.org X-Gm-Message-State: AOJu0YyDk4VBscLtcT0D7rVdioynsdP7+xEK/2O6bWY2N2dIyiGNVwJb 7iKBj7OyVud1ge9e48VM+5du4x2b0vi8HvbaYrnLweD0HzOT6rgDN4oWgDc6tqIVa7GZVVrkYCs iCJvoog== X-Google-Smtp-Source: AGHT+IErLLqmD/PORlhyxU7jOUm4C+LioX2IifX5+KrKCfJkXml7M7iR2w0tUMSLgBWIeNxBWpYKDngkc0Y= X-Received: from pjtt1.prod.google.com ([2002:a17:90a:1c81:b0:332:8389:c569]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:903:2442:b0:24c:ed95:2725 with SMTP id d9443c01a7336-27cc28bc310mr34259705ad.4.1758641866139; Tue, 23 Sep 2025 08:37:46 -0700 (PDT) Reply-To: Sean Christopherson Date: Tue, 23 Sep 2025 08:37:37 -0700 In-Reply-To: <20250923153738.1875174-1-seanjc@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250923153738.1875174-1-seanjc@google.com> X-Mailer: git-send-email 2.51.0.534.gc79095c0ca-goog Message-ID: <20250923153738.1875174-2-seanjc@google.com> Subject: [PATCH v3 1/2] KVM: x86: Add helper to retrieve current value of user return MSR From: Sean Christopherson To: Sean Christopherson , Paolo Bonzini Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Hou Wenlong , Xiaoyao Li , Lai Jiangshan Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Hou Wenlong In the user return MSR support, the cached value is always the hardware value of the specific MSR. Therefore, add a helper to retrieve the cached value, which can replace the need for RDMSR, for example, to allow SEV-ES guests to restore the correct host hardware value without using RDMSR. Cc: stable@vger.kernel.org Signed-off-by: Hou Wenlong [sean: drop "cache" from the name, make it a one-liner, tag for stable] Reviewed-by: Xiaoyao Li Signed-off-by: Sean Christopherson --- arch/x86/include/asm/kvm_host.h | 1 + arch/x86/kvm/x86.c | 6 ++++++ 2 files changed, 7 insertions(+) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_hos= t.h index 17772513b9cc..14236006266b 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -2376,6 +2376,7 @@ int kvm_add_user_return_msr(u32 msr); int kvm_find_user_return_msr(u32 msr); int kvm_set_user_return_msr(unsigned index, u64 val, u64 mask); void kvm_user_return_msr_update_cache(unsigned int index, u64 val); +u64 kvm_get_user_return_msr(unsigned int slot); =20 static inline bool kvm_is_supported_user_return_msr(u32 msr) { diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index e07936efacd4..801bf6172a21 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -675,6 +675,12 @@ void kvm_user_return_msr_update_cache(unsigned int slo= t, u64 value) } EXPORT_SYMBOL_GPL(kvm_user_return_msr_update_cache); =20 +u64 kvm_get_user_return_msr(unsigned int slot) +{ + return this_cpu_ptr(user_return_msrs)->values[slot].curr; +} +EXPORT_SYMBOL_GPL(kvm_get_user_return_msr); + static void drop_user_return_notifiers(void) { struct kvm_user_return_msrs *msrs =3D this_cpu_ptr(user_return_msrs); --=20 2.51.0.534.gc79095c0ca-goog