Received-SPF: pass (google.com: domain of linux-kernel+bounces-47832-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:4601:e00::3 as permitted sender) client-ip=2604:1380:4601:e00::3;
Date: Thu, 1 Feb 2024 10:34:48 +0200
From: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, 
	Zixi Chen <zixchen@redhat.com>, Adam Dunlap <acdunlap@google.com>, 
	Xiaoyao Li <xiaoyao.li@intel.com>, Kai Huang <kai.huang@intel.com>, 
	Dave Hansen <dave.hansen@linux.intel.com>, Thomas Gleixner <tglx@linutronix.de>, 
	Ingo Molnar <mingo@kernel.org>, x86@kernel.org, stable@vger.kernel.org
Subject: Re: [PATCH v2 2/2] x86/cpu/intel: Detect TME keyid bits before
 setting MTRR mask registers
Message-ID: <qtzc3jejjsvxpa6sz3zgoelf77ejr7fioxdaw2o5ezuxevetks@kcwjgzp2gi2u>
References: <20240131230902.1867092-1-pbonzini@redhat.com>
 <20240131230902.1867092-3-pbonzini@redhat.com>
Precedence: bulk
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20240131230902.1867092-3-pbonzini@redhat.com>

On Thu, Feb 01, 2024 at 12:09:02AM +0100, Paolo Bonzini wrote:
> MKTME repurposes the high bit of physical address to key id for encryption
> key and, even though MAXPHYADDR in CPUID[0x80000008] remains the same,
> the valid bits in the MTRR mask register are based on the reduced number
> of physical address bits.
> 
> detect_tme() in arch/x86/kernel/cpu/intel.c detects TME and subtracts
> it from the total usable physical bits, but it is called too late.
> Move the call to early_init_intel() so that it is called in setup_arch(),
> before MTRRs are setup.
> 
> This fixes boot on TDX-enabled systems, which until now only worked with
> "disable_mtrr_cleanup".  Without the patch, the values written to the
> MTRRs mask registers were 52-bit wide (e.g. 0x000fffff_80000800) and
> the writes failed; with the patch, the values are 46-bit wide, which
> matches the reduced MAXPHYADDR that is shown in /proc/cpuinfo.
> 
> Reported-by: Zixi Chen <zixchen@redhat.com>
> Cc: Adam Dunlap <acdunlap@google.com>
> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> Cc: Xiaoyao Li <xiaoyao.li@intel.com>
> Cc: Kai Huang <kai.huang@intel.com>
> Cc: Dave Hansen <dave.hansen@linux.intel.com>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Ingo Molnar <mingo@kernel.org>
> Cc: x86@kernel.org
> Cc: stable@vger.kernel.org
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>

-- 
  Kiryl Shutsemau / Kirill A. Shutemov