Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Tue, 20 Dec 2022 09:56:19 +0100
From:   Peter Zijlstra <peterz@infradead.org>
To:     Xin Li <xin3.li@intel.com>
Cc:     linux-kernel@vger.kernel.org, x86@kernel.org, kvm@vger.kernel.org,
        tglx@linutronix.de, mingo@redhat.com, bp@alien8.de,
        dave.hansen@linux.intel.com, hpa@zytor.com,
        andrew.cooper3@citrix.com, seanjc@google.com, pbonzini@redhat.com,
        ravi.v.shankar@intel.com
Subject: Re: [RFC PATCH 14/32] x86/fred: header file with FRED definitions
Message-ID: <Y6F4s0K2b2G8aMve@hirez.programming.kicks-ass.net>
References: <20221220063658.19271-1-xin3.li@intel.com>
 <20221220063658.19271-15-xin3.li@intel.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20221220063658.19271-15-xin3.li@intel.com>
Precedence: bulk


> +/*
> + * FRED return instructions
> + *
> + * Replace with "ERETS"/"ERETU" once binutils support FRED return instructions.

binutils version that supports these instructions goes here...

> + */
> +#define ERETS			_ASM_BYTES(0xf2,0x0f,0x01,0xca)
> +#define ERETU			_ASM_BYTES(0xf3,0x0f,0x01,0xca)
> +
> +/*
> + * Event stack level macro for the FRED_STKLVLS MSR.
> + * Usage example: FRED_STKLVL(X86_TRAP_DF, 3)
> + * Multiple values can be ORd together.
> + */
> +#define FRED_STKLVL(v,l)	(_AT(unsigned long, l) << (2*(v)))
> +
> +/* FRED_CONFIG MSR */
> +#define FRED_CONFIG_CSL_MASK		0x3
> +#define FRED_CONFIG_SHADOW_STACK_SPACE	_BITUL(3)
> +#define FRED_CONFIG_REDZONE(b)		__ALIGN_KERNEL_MASK((b), _UL(0x3f))
> +#define FRED_CONFIG_INT_STKLVL(l)	(_AT(unsigned long, l) << 9)
> +#define FRED_CONFIG_ENTRYPOINT(p)	_AT(unsigned long, (p))
> +
> +/* FRED event type and vector bit width and counts */
> +#define FRED_EVENT_TYPE_BITS		3 /* only 3 bits used in FRED 3.0 */
> +#define FRED_EVENT_TYPE_COUNT		_BITUL(FRED_EVENT_TYPE_BITS)
> +#define FRED_EVENT_VECTOR_BITS		8
> +#define FRED_EVENT_VECTOR_COUNT		_BITUL(FRED_EVENT_VECTOR_BITS)
> +
> +/* FRED EVENT_TYPE_OTHER vector numbers */
> +#define FRED_SYSCALL			1
> +#define FRED_SYSENTER			2
> +
> +/* Flags above the CS selector (regs->csl) */
> +#define FRED_CSL_ENABLE_NMI		_BITUL(28)
> +#define FRED_CSL_ALLOW_SINGLE_STEP	_BITUL(25)
> +#define FRED_CSL_INTERRUPT_SHADOW	_BITUL(24)

What's the state of IBT WAIT-FOR-ENDBR vs this? That really should also
get a high CS bit.