From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pg1-f201.google.com (mail-pg1-f201.google.com [209.85.215.201]) (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 B44E22D2485 for ; Fri, 19 Sep 2025 21:38:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.215.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758317892; cv=none; b=e/69iDALUY590Jzo8gl+xAoy2qeOCnfC+tHhHWMkgffMI1BE1nN6WUTM/TEOQIp6bumEt+mBES/2IDBX2+ruzMBa+twy1bU2vcJHOmMS7Ph6G2Hvxo7jvD0uxh8eWBtk0eStCA3n0fBMNMAcwnS59E53RJ+Z/n6ytoOjNHBnfJE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758317892; c=relaxed/simple; bh=NyO3OCkrgrNJyiVrALtIf7HEXPoVs1ZzdtlJEqQJGZ0=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=K0BERNpWucfEM+jirr8SWBiRNL+kC3DbvG6Yoi7vLx6a/IYM6qha+u128173mvxXx1ZsTD+UB0kHTkINZKAfpP9m57OXKiK0bQAMj35SOxxMs9/jeRToGqRfNL4RXHyEP3nepdvXTxP2QUNbp+KQCY6WD3RxTy5W1q9vbwa3iTI= 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=j4Rj4Kjd; arc=none smtp.client-ip=209.85.215.201 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="j4Rj4Kjd" Received: by mail-pg1-f201.google.com with SMTP id 41be03b00d2f7-b4f87c691a7so3829654a12.3 for ; Fri, 19 Sep 2025 14:38:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1758317890; x=1758922690; 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=LCcXeK8XcV62V6MRvysCvORWa4slmpddR0tHqtIttxk=; b=j4Rj4KjdCtPh4mF90j3mihDCv9dv5E+2AMeMqq4CcamqlG1dvI57ZS10RX5cuKIsLe ru64ijJWu8h7RK5cWwhMzWIpPkRZDRtOk+ZksdYmtaqaBvf0vbdw3XTuNKVLs+IRQtzL lmzygd0fwV8QyoGqyJ8tQw0KxyA94v/5HG5rK8oibgq4hdNR9yWODTseAHKAGMSQNMBX fnu02qwDDt4nNoB9bqM4B/367luBLJggh48ofeNxK41ovCBQ6DHxi1NUiiOlSS4SIKE2 +BTEfGblzKuAfWkFjgAzficWPjnW8zNxRgGI3rczpkVMVQIpss8ipLe3sXHSc4FXGQFm tGVQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1758317890; x=1758922690; 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=LCcXeK8XcV62V6MRvysCvORWa4slmpddR0tHqtIttxk=; b=UJU0QvOXW7mV4PvWtrI+tzcY30HzDGboMFvQ2v4gMia5ZnOBvErBSu/Qpay2XCia9M bNgtgg71fhJoNmA4Fc3eLI9RGv3PT5p6CUbz2Ua8Rsdk+FAfAdlZvNemtmdbiWLzuRmn JVwsSvrekyr6PR0z4w+PPEuuiV2wg9uelC0JlX9F0x6xGnu/GwCwzPeOIrJXk1JfLEKO k0HdxHHyGrJv8Fs+4AzYZKTbAYgbU8X1fz+wZibK1TLpBrsiA0cwZmrhrKI6BNOrbh/h I1pr4DeY0X+EHsibfB/RynWnODvZPo76mHFF5wJPTFdFGggNJiZNzlL53zHP3D7+Gk9B AbSg== X-Gm-Message-State: AOJu0Yw5Cg/7VXWYs6LtvcfcB9YVFdNgNU6GJxQJnBKUaHUmY8EroCD3 I7oh4VuLAUToXqW2sXH+NCUquOlQE0NsXbSVCHyCMDTQvWIhYMMM8f+s52LtxNUCd3FCQvNSpJ3 IMCshEA== X-Google-Smtp-Source: AGHT+IEmokOFSO/BZLJz9nefMHMY4QoIe0UUWs2Gq+mwIsFKXPU+hnaQYX4XneyvMPqRBMvMZrWMSQMtboI= X-Received: from pjbnd17.prod.google.com ([2002:a17:90b:4cd1:b0:32e:b34b:92eb]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a20:939f:b0:263:bee9:1ac8 with SMTP id adf61e73a8af0-2927031a2d5mr7191684637.28.1758317889963; Fri, 19 Sep 2025 14:38:09 -0700 (PDT) Reply-To: Sean Christopherson Date: Fri, 19 Sep 2025 14:38:05 -0700 In-Reply-To: <20250919213806.1582673-1-seanjc@google.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250919213806.1582673-1-seanjc@google.com> X-Mailer: git-send-email 2.51.0.470.ga7dc726c21-goog Message-ID: <20250919213806.1582673-2-seanjc@google.com> Subject: [PATCH v2 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 , Lai Jiangshan 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] 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_host.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); 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 slot, u64 value) } EXPORT_SYMBOL_GPL(kvm_user_return_msr_update_cache); +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 = this_cpu_ptr(user_return_msrs); -- 2.51.0.470.ga7dc726c21-goog