From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id E1AB2C54E58 for ; Wed, 20 Mar 2024 18:13:51 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1rn0Qr-00053C-Rh; Wed, 20 Mar 2024 14:12:57 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rn0Qn-00052F-Ge for qemu-devel@nongnu.org; Wed, 20 Mar 2024 14:12:54 -0400 Received: from mgamail.intel.com ([198.175.65.15]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rn0QQ-0000ac-F1 for qemu-devel@nongnu.org; Wed, 20 Mar 2024 14:12:53 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1710958351; x=1742494351; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=Vnbag9q3xQRvF0qzbjgLy7tYXm8Ph98PFJ3DvYqpeYA=; b=PhnYYZ/fd7zBS6E2wL44Ufz0sqC3+7PoOI9Ifut0zE8OweCVZ+PiVppl dS4bdBsEvoNrE3diYJ3kl/pnaJqOYiPKH5pOrda8mh6oRavl2bT1lxKsP NQNN3HKx+chjjG6tsb+X4KurJd+lwwXEC3TzAPP+71S1rhhnCo+t1TS+A Cp9TJBg/rbjgfFjCUAzTSFE7cXLXOddk7fsvTiIRArvXB2Ha0uUiRw8Uz XLQ1tP2u+YTHElprM4zas30QXslIKpVihvJptFJpT0k5TplMyIJBvj9Mf +tV9iwcb7LDyiAY6tkQOIlgddm1FHiT9W2j1JZMkTDlJuHT1QhHsKnimh w==; X-IronPort-AV: E=McAfee;i="6600,9927,11019"; a="9697215" X-IronPort-AV: E=Sophos;i="6.07,140,1708416000"; d="scan'208";a="9697215" Received: from orviesa010.jf.intel.com ([10.64.159.150]) by orvoesa107.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Mar 2024 11:12:24 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.07,140,1708416000"; d="scan'208";a="14142999" Received: from ls.sc.intel.com (HELO localhost) ([172.25.112.31]) by orviesa010-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Mar 2024 11:12:24 -0700 Date: Wed, 20 Mar 2024 11:12:23 -0700 From: Isaku Yamahata To: Michael Roth Cc: qemu-devel@nongnu.org, kvm@vger.kernel.org, Tom Lendacky , Paolo Bonzini , Daniel P =?utf-8?B?LiBCZXJyYW5nw6k=?= , Markus Armbruster , Pankaj Gupta , Xiaoyao Li , Isaku Yamahata , isaku.yamahata@intel.com Subject: Re: [PATCH v3 48/49] hw/i386/sev: Use guest_memfd for legacy ROMs Message-ID: <20240320181223.GG1994522@ls.amr.corp.intel.com> References: <20240320083945.991426-1-michael.roth@amd.com> <20240320083945.991426-49-michael.roth@amd.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20240320083945.991426-49-michael.roth@amd.com> Received-SPF: pass client-ip=198.175.65.15; envelope-from=isaku.yamahata@intel.com; helo=mgamail.intel.com X-Spam_score_int: -24 X-Spam_score: -2.5 X-Spam_bar: -- X-Spam_report: (-2.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.417, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Wed, Mar 20, 2024 at 03:39:44AM -0500, Michael Roth wrote: > TODO: make this SNP-specific if TDX disables legacy ROMs in general TDX disables pc.rom, not disable isa-bios. IIRC, TDX doesn't need pc pflash. Xiaoyao can chime in. Thanks, > > Current SNP guest kernels will attempt to access these regions with > with C-bit set, so guest_memfd is needed to handle that. Otherwise, > kvm_convert_memory() will fail when the guest kernel tries to access it > and QEMU attempts to call KVM_SET_MEMORY_ATTRIBUTES to set these ranges > to private. > > Whether guests should actually try to access ROM regions in this way (or > need to deal with legacy ROM regions at all), is a separate issue to be > addressed on kernel side, but current SNP guest kernels will exhibit > this behavior and so this handling is needed to allow QEMU to continue > running existing SNP guest kernels. > > Signed-off-by: Michael Roth > --- > hw/i386/pc.c | 13 +++++++++---- > hw/i386/pc_sysfw.c | 13 ++++++++++--- > 2 files changed, 19 insertions(+), 7 deletions(-) > > diff --git a/hw/i386/pc.c b/hw/i386/pc.c > index feb7a93083..5feaeb43ee 100644 > --- a/hw/i386/pc.c > +++ b/hw/i386/pc.c > @@ -1011,10 +1011,15 @@ void pc_memory_init(PCMachineState *pcms, > pc_system_firmware_init(pcms, rom_memory); > > option_rom_mr = g_malloc(sizeof(*option_rom_mr)); > - memory_region_init_ram(option_rom_mr, NULL, "pc.rom", PC_ROM_SIZE, > - &error_fatal); > - if (pcmc->pci_enabled) { > - memory_region_set_readonly(option_rom_mr, true); > + if (machine_require_guest_memfd(machine)) { > + memory_region_init_ram_guest_memfd(option_rom_mr, NULL, "pc.rom", > + PC_ROM_SIZE, &error_fatal); > + } else { > + memory_region_init_ram(option_rom_mr, NULL, "pc.rom", PC_ROM_SIZE, > + &error_fatal); > + if (pcmc->pci_enabled) { > + memory_region_set_readonly(option_rom_mr, true); > + } > } > memory_region_add_subregion_overlap(rom_memory, > PC_ROM_MIN_VGA, > diff --git a/hw/i386/pc_sysfw.c b/hw/i386/pc_sysfw.c > index 9dbb3f7337..850f86edd4 100644 > --- a/hw/i386/pc_sysfw.c > +++ b/hw/i386/pc_sysfw.c > @@ -54,8 +54,13 @@ static void pc_isa_bios_init(MemoryRegion *rom_memory, > /* map the last 128KB of the BIOS in ISA space */ > isa_bios_size = MIN(flash_size, 128 * KiB); > isa_bios = g_malloc(sizeof(*isa_bios)); > - memory_region_init_ram(isa_bios, NULL, "isa-bios", isa_bios_size, > - &error_fatal); > + if (machine_require_guest_memfd(current_machine)) { > + memory_region_init_ram_guest_memfd(isa_bios, NULL, "isa-bios", > + isa_bios_size, &error_fatal); > + } else { > + memory_region_init_ram(isa_bios, NULL, "isa-bios", isa_bios_size, > + &error_fatal); > + } > memory_region_add_subregion_overlap(rom_memory, > 0x100000 - isa_bios_size, > isa_bios, > @@ -68,7 +73,9 @@ static void pc_isa_bios_init(MemoryRegion *rom_memory, > ((uint8_t*)flash_ptr) + (flash_size - isa_bios_size), > isa_bios_size); > > - memory_region_set_readonly(isa_bios, true); > + if (!machine_require_guest_memfd(current_machine)) { > + memory_region_set_readonly(isa_bios, true); > + } > } > > static PFlashCFI01 *pc_pflash_create(PCMachineState *pcms, > -- > 2.25.1 > > -- Isaku Yamahata