From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 81D961F9A99; Tue, 17 Dec 2024 17:33:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734456823; cv=none; b=nCpjUIvBI5vgEJowbBqdA7T8SPhnqUXg1tF57ZIhHBpaN821VYBLVmC+Icjh010fuIajZ9ngahQeSrm6wiku7j16XWGmj1TQeTlljvl31HZFo+tFxsKkOMdlfdWo6XdtXtxAtI4bU5M0FI3Y5+Uzu6o5zbVzncJljsyffvwhi8c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734456823; c=relaxed/simple; bh=aRa0GHtJTkZD2/JTVJpzZuCoXr+ACWdd+MfJ1epCKZE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=GpQzdhBBHioTVDEuRRdxIGL4/8qyTIMd3lEklAKRuoG1BwJ0X5UTjKKvfv+E+m5hVGBIr2QJiRxpnkPPZ2ghpqE1Z+7eBdWBqLLuNnbL4E9kkYkDNtwbdX9UsCWEDTaU99s0y9wqtz1N0mFcKcw22kFnJGn4NAYePUJRJJsmqrg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=gljf1ke3; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="gljf1ke3" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 06D33C4CED3; Tue, 17 Dec 2024 17:33:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1734456823; bh=aRa0GHtJTkZD2/JTVJpzZuCoXr+ACWdd+MfJ1epCKZE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=gljf1ke3vXZXPil8sBGU/Aa+rrlOoYf7VE6rNZvlwHiVXRKP5CRQkE2Aj3q2tTWUB eZrgR1hDNsFQpC4o3V/3ORyWHqPhBe6nLWepEQ3g6pi1DTKGcuEWSRZAYaOH8cIhiZ PBOR6Au3J7UBQTXw8fVOgQ+WR7CQwcMsDsa/gRDA= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Andrew Cooper , Juergen Gross , Jan Beulich Subject: [PATCH 6.12 172/172] x86/xen: remove hypercall page Date: Tue, 17 Dec 2024 18:08:48 +0100 Message-ID: <20241217170553.478653587@linuxfoundation.org> X-Mailer: git-send-email 2.47.1 In-Reply-To: <20241217170546.209657098@linuxfoundation.org> References: <20241217170546.209657098@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Juergen Gross commit 7fa0da5373685e7ed249af3fa317ab1e1ba8b0a6 upstream. The hypercall page is no longer needed. It can be removed, as from the Xen perspective it is optional. But, from Linux's perspective, it removes naked RET instructions that escape the speculative protections that Call Depth Tracking and/or Untrain Ret are trying to achieve. This is part of XSA-466 / CVE-2024-53241. Reported-by: Andrew Cooper Signed-off-by: Juergen Gross Reviewed-by: Andrew Cooper Reviewed-by: Jan Beulich Signed-off-by: Greg Kroah-Hartman --- arch/x86/include/asm/xen/hypercall.h | 2 -- arch/x86/kernel/callthunks.c | 5 ----- arch/x86/xen/enlighten.c | 2 -- arch/x86/xen/enlighten_hvm.c | 9 +-------- arch/x86/xen/enlighten_pvh.c | 7 ------- arch/x86/xen/xen-head.S | 23 ----------------------- 6 files changed, 1 insertion(+), 47 deletions(-) --- a/arch/x86/include/asm/xen/hypercall.h +++ b/arch/x86/include/asm/xen/hypercall.h @@ -88,8 +88,6 @@ struct xen_dm_op_buf; * there aren't more than 5 arguments...) */ -extern struct { char _entry[32]; } hypercall_page[]; - void xen_hypercall_func(void); DECLARE_STATIC_CALL(xen_hypercall, xen_hypercall_func); --- a/arch/x86/kernel/callthunks.c +++ b/arch/x86/kernel/callthunks.c @@ -143,11 +143,6 @@ static bool skip_addr(void *dest) dest < (void*)relocate_kernel + KEXEC_CONTROL_CODE_MAX_SIZE) return true; #endif -#ifdef CONFIG_XEN - if (dest >= (void *)hypercall_page && - dest < (void*)hypercall_page + PAGE_SIZE) - return true; -#endif return false; } --- a/arch/x86/xen/enlighten.c +++ b/arch/x86/xen/enlighten.c @@ -22,8 +22,6 @@ #include "xen-ops.h" -EXPORT_SYMBOL_GPL(hypercall_page); - DEFINE_STATIC_CALL(xen_hypercall, xen_hypercall_hvm); EXPORT_STATIC_CALL_TRAMP(xen_hypercall); --- a/arch/x86/xen/enlighten_hvm.c +++ b/arch/x86/xen/enlighten_hvm.c @@ -106,15 +106,8 @@ static void __init init_hvm_pv_info(void /* PVH set up hypercall page in xen_prepare_pvh(). */ if (xen_pvh_domain()) pv_info.name = "Xen PVH"; - else { - u64 pfn; - uint32_t msr; - + else pv_info.name = "Xen HVM"; - msr = cpuid_ebx(base + 2); - pfn = __pa(hypercall_page); - wrmsr_safe(msr, (u32)pfn, (u32)(pfn >> 32)); - } xen_setup_features(); --- a/arch/x86/xen/enlighten_pvh.c +++ b/arch/x86/xen/enlighten_pvh.c @@ -129,17 +129,10 @@ static void __init pvh_arch_setup(void) void __init xen_pvh_init(struct boot_params *boot_params) { - u32 msr; - u64 pfn; - xen_pvh = 1; xen_domain_type = XEN_HVM_DOMAIN; xen_start_flags = pvh_start_info.flags; - msr = cpuid_ebx(xen_cpuid_base() + 2); - pfn = __pa(hypercall_page); - wrmsr_safe(msr, (u32)pfn, (u32)(pfn >> 32)); - x86_init.oem.arch_setup = pvh_arch_setup; x86_init.oem.banner = xen_banner; --- a/arch/x86/xen/xen-head.S +++ b/arch/x86/xen/xen-head.S @@ -22,28 +22,6 @@ #include #include -.pushsection .noinstr.text, "ax" - .balign PAGE_SIZE -SYM_CODE_START(hypercall_page) - .rept (PAGE_SIZE / 32) - UNWIND_HINT_FUNC - ANNOTATE_NOENDBR - ANNOTATE_UNRET_SAFE - ret - /* - * Xen will write the hypercall page, and sort out ENDBR. - */ - .skip 31, 0xcc - .endr - -#define HYPERCALL(n) \ - .equ xen_hypercall_##n, hypercall_page + __HYPERVISOR_##n * 32; \ - .type xen_hypercall_##n, @function; .size xen_hypercall_##n, 32 -#include -#undef HYPERCALL -SYM_CODE_END(hypercall_page) -.popsection - #ifdef CONFIG_XEN_PV __INIT SYM_CODE_START(startup_xen) @@ -198,7 +176,6 @@ SYM_FUNC_END(xen_hypercall_intel) #else # define FEATURES_DOM0 0 #endif - ELFNOTE(Xen, XEN_ELFNOTE_HYPERCALL_PAGE, _ASM_PTR hypercall_page) ELFNOTE(Xen, XEN_ELFNOTE_SUPPORTED_FEATURES, .long FEATURES_PV | FEATURES_PVH | FEATURES_DOM0) ELFNOTE(Xen, XEN_ELFNOTE_LOADER, .asciz "generic")