Received-SPF: pass (google.com: domain of linux-kernel+bounces-45907-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.80.249 as permitted sender) client-ip=147.75.80.249;
Date: Wed, 31 Jan 2024 07:21:20 -0000
From: "tip-bot2 for H. Peter Anvin (Intel)" <tip-bot2@linutronix.de>
Sender: tip-bot2@linutronix.de
Reply-to: linux-kernel@vger.kernel.org
To: linux-tip-commits@vger.kernel.org
Subject: [tip: x86/fred] x86/fred: No ESPFIX needed when FRED is enabled
Cc: "H. Peter Anvin (Intel)" <hpa@zytor.com>, Xin Li <xin3.li@intel.com>,
 Thomas Gleixner <tglx@linutronix.de>, Shan Kang <shan.kang@intel.com>,
 x86@kernel.org, linux-kernel@vger.kernel.org
In-Reply-To: <20231205105030.8698-20-xin3.li@intel.com>
References: <20231205105030.8698-20-xin3.li@intel.com>
Precedence: bulk
MIME-Version: 1.0
Message-ID: <170668568002.398.1889543253223143145.tip-bot2@tip-bot2>
Robot-ID: <tip-bot2@linutronix.de>
Robot-Unsubscribe:
 Contact <mailto:tglx@linutronix.de> to get blacklisted from these emails
Precedence: bulk
Content-Type: text/plain; charset="utf-8"
Content-Transfer-Encoding: 7bit

The following commit has been merged into the x86/fred branch of tip:

Commit-ID:     d0fb796dc3475cf71d788ec960d8ed5de4d7a429
Gitweb:        https://git.kernel.org/tip/d0fb796dc3475cf71d788ec960d8ed5de4d7a429
Author:        H. Peter Anvin (Intel) <hpa@zytor.com>
AuthorDate:    Tue, 05 Dec 2023 02:50:08 -08:00
Committer:     Borislav Petkov (AMD) <bp@alien8.de>
CommitterDate: Tue, 30 Jan 2024 18:20:35 +01:00

x86/fred: No ESPFIX needed when FRED is enabled

Because FRED always restores the full value of %rsp, ESPFIX is
no longer needed when it's enabled.

Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com>
Signed-off-by: Xin Li <xin3.li@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Shan Kang <shan.kang@intel.com>
Link: https://lore.kernel.org/r/20231205105030.8698-20-xin3.li@intel.com

---
 arch/x86/kernel/espfix_64.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/arch/x86/kernel/espfix_64.c b/arch/x86/kernel/espfix_64.c
index 16f9814..6726e04 100644
--- a/arch/x86/kernel/espfix_64.c
+++ b/arch/x86/kernel/espfix_64.c
@@ -106,6 +106,10 @@ void __init init_espfix_bsp(void)
 	pgd_t *pgd;
 	p4d_t *p4d;
 
+	/* FRED systems always restore the full value of %rsp */
+	if (cpu_feature_enabled(X86_FEATURE_FRED))
+		return;
+
 	/* Install the espfix pud into the kernel page directory */
 	pgd = &init_top_pgt[pgd_index(ESPFIX_BASE_ADDR)];
 	p4d = p4d_alloc(&init_mm, pgd, ESPFIX_BASE_ADDR);
@@ -129,6 +133,10 @@ void init_espfix_ap(int cpu)
 	void *stack_page;
 	pteval_t ptemask;
 
+	/* FRED systems always restore the full value of %rsp */
+	if (cpu_feature_enabled(X86_FEATURE_FRED))
+		return;
+
 	/* We only have to do this once... */
 	if (likely(per_cpu(espfix_stack, cpu)))
 		return;		/* Already initialized */