From: "Michael S. Tsirkin" <mst@redhat.com>
To: Bernhard Beschow <shentey@gmail.com>
Cc: qemu-devel@nongnu.org, "Sergio Lopez" <slp@redhat.com>,
"Richard Henderson" <richard.henderson@linaro.org>,
"Eduardo Habkost" <eduardo@habkost.net>,
"Philippe Mathieu-Daudé" <philmd@linaro.org>,
"Marcel Apfelbaum" <marcel.apfelbaum@gmail.com>,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Michael Roth" <michael.roth@amd.com>
Subject: Re: [PATCH v3 6/6] hw/i386/pc_sysfw: Alias rather than copy isa-bios region
Date: Tue, 21 May 2024 03:42:10 -0400 [thread overview]
Message-ID: <20240521034158-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <20240508175507.22270-7-shentey@gmail.com>
On Wed, May 08, 2024 at 07:55:07PM +0200, Bernhard Beschow wrote:
> In the -bios case the "isa-bios" memory region is an alias to the BIOS mapped
> to the top of the 4G memory boundary. Do the same in the -pflash case, but only
> for new machine versions for migration compatibility. This establishes common
> behavior and makes pflash commands work in the "isa-bios" region which some
> real-world legacy bioses rely on.
>
> Note that in the sev_enabled() case, the "isa-bios" memory region in the -pflash
> case will now also point to encrypted memory, just like it already does in the
> -bios case.
>
> When running `info mtree` before and after this commit with
> `qemu-system-x86_64 -S -drive \
> if=pflash,format=raw,readonly=on,file=/usr/share/qemu/bios-256k.bin` and running
> `diff -u before.mtree after.mtree` results in the following changes in the
> memory tree:
>
> --- before.mtree
> +++ after.mtree
> @@ -71,7 +71,7 @@
> 0000000000000000-ffffffffffffffff (prio -1, i/o): pci
> 00000000000a0000-00000000000bffff (prio 1, i/o): vga-lowmem
> 00000000000c0000-00000000000dffff (prio 1, rom): pc.rom
> - 00000000000e0000-00000000000fffff (prio 1, rom): isa-bios
> + 00000000000e0000-00000000000fffff (prio 1, romd): alias isa-bios @system.flash0 0000000000020000-000000000003ffff
> 00000000000a0000-00000000000bffff (prio 1, i/o): alias smram-region @pci 00000000000a0000-00000000000bffff
> 00000000000c0000-00000000000c3fff (prio 1, i/o): alias pam-pci @pci 00000000000c0000-00000000000c3fff
> 00000000000c4000-00000000000c7fff (prio 1, i/o): alias pam-pci @pci 00000000000c4000-00000000000c7fff
> @@ -108,7 +108,7 @@
> 0000000000000000-ffffffffffffffff (prio -1, i/o): pci
> 00000000000a0000-00000000000bffff (prio 1, i/o): vga-lowmem
> 00000000000c0000-00000000000dffff (prio 1, rom): pc.rom
> - 00000000000e0000-00000000000fffff (prio 1, rom): isa-bios
> + 00000000000e0000-00000000000fffff (prio 1, romd): alias isa-bios @system.flash0 0000000000020000-000000000003ffff
> 00000000000a0000-00000000000bffff (prio 1, i/o): alias smram-region @pci 00000000000a0000-00000000000bffff
> 00000000000c0000-00000000000c3fff (prio 1, i/o): alias pam-pci @pci 00000000000c0000-00000000000c3fff
> 00000000000c4000-00000000000c7fff (prio 1, i/o): alias pam-pci @pci 00000000000c4000-00000000000c7fff
> @@ -131,11 +131,14 @@
> memory-region: pc.ram
> 0000000000000000-0000000007ffffff (prio 0, ram): pc.ram
>
> +memory-region: system.flash0
> + 00000000fffc0000-00000000ffffffff (prio 0, romd): system.flash0
> +
> memory-region: pci
> 0000000000000000-ffffffffffffffff (prio -1, i/o): pci
> 00000000000a0000-00000000000bffff (prio 1, i/o): vga-lowmem
> 00000000000c0000-00000000000dffff (prio 1, rom): pc.rom
> - 00000000000e0000-00000000000fffff (prio 1, rom): isa-bios
> + 00000000000e0000-00000000000fffff (prio 1, romd): alias isa-bios @system.flash0 0000000000020000-000000000003ffff
>
> memory-region: smram
> 00000000000a0000-00000000000bffff (prio 0, ram): alias smram-low @pc.ram 00000000000a0000-00000000000bffff
>
> Note that in both cases the "system" memory region contains the entry
>
> 00000000fffc0000-00000000ffffffff (prio 0, romd): system.flash0
>
> but the "system.flash0" memory region only appears standalone when "isa-bios" is
> an alias.
>
> Signed-off-by: Bernhard Beschow <shentey@gmail.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
feel free to queue
> ---
> include/hw/i386/pc.h | 1 +
> hw/i386/pc.c | 1 +
> hw/i386/pc_piix.c | 3 +++
> hw/i386/pc_q35.c | 2 ++
> hw/i386/pc_sysfw.c | 8 +++++++-
> 5 files changed, 14 insertions(+), 1 deletion(-)
>
> diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
> index e52290916c..ad9c3d9ba8 100644
> --- a/include/hw/i386/pc.h
> +++ b/include/hw/i386/pc.h
> @@ -119,6 +119,7 @@ struct PCMachineClass {
> bool enforce_aligned_dimm;
> bool broken_reserved_end;
> bool enforce_amd_1tb_hole;
> + bool isa_bios_alias;
>
> /* generate legacy CPU hotplug AML */
> bool legacy_cpu_hotplug;
> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> index 46235466d7..4878705af7 100644
> --- a/hw/i386/pc.c
> +++ b/hw/i386/pc.c
> @@ -1812,6 +1812,7 @@ static void pc_machine_class_init(ObjectClass *oc, void *data)
> pcmc->has_reserved_memory = true;
> pcmc->enforce_aligned_dimm = true;
> pcmc->enforce_amd_1tb_hole = true;
> + pcmc->isa_bios_alias = true;
> /* BIOS ACPI tables: 128K. Other BIOS datastructures: less than 4K reported
> * to be used at the moment, 32K should be enough for a while. */
> pcmc->acpi_data_size = 0x20000 + 0x8000;
> diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
> index 8850c49c66..d4e9deb509 100644
> --- a/hw/i386/pc_piix.c
> +++ b/hw/i386/pc_piix.c
> @@ -525,12 +525,15 @@ DEFINE_I440FX_MACHINE(v9_1, "pc-i440fx-9.1", NULL,
>
> static void pc_i440fx_9_0_machine_options(MachineClass *m)
> {
> + PCMachineClass *pcmc = PC_MACHINE_CLASS(m);
> +
> pc_i440fx_9_1_machine_options(m);
> m->alias = NULL;
> m->is_default = false;
>
> compat_props_add(m->compat_props, hw_compat_9_0, hw_compat_9_0_len);
> compat_props_add(m->compat_props, pc_compat_9_0, pc_compat_9_0_len);
> + pcmc->isa_bios_alias = false;
> }
>
> DEFINE_I440FX_MACHINE(v9_0, "pc-i440fx-9.0", NULL,
> diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
> index bb53a51ac1..bd7db4abac 100644
> --- a/hw/i386/pc_q35.c
> +++ b/hw/i386/pc_q35.c
> @@ -378,10 +378,12 @@ DEFINE_Q35_MACHINE(v9_1, "pc-q35-9.1", NULL,
>
> static void pc_q35_9_0_machine_options(MachineClass *m)
> {
> + PCMachineClass *pcmc = PC_MACHINE_CLASS(m);
> pc_q35_9_1_machine_options(m);
> m->alias = NULL;
> compat_props_add(m->compat_props, hw_compat_9_0, hw_compat_9_0_len);
> compat_props_add(m->compat_props, pc_compat_9_0, pc_compat_9_0_len);
> + pcmc->isa_bios_alias = false;
> }
>
> DEFINE_Q35_MACHINE(v9_0, "pc-q35-9.0", NULL,
> diff --git a/hw/i386/pc_sysfw.c b/hw/i386/pc_sysfw.c
> index 82d37cb376..ac88ad4eb9 100644
> --- a/hw/i386/pc_sysfw.c
> +++ b/hw/i386/pc_sysfw.c
> @@ -135,6 +135,7 @@ static void pc_system_flash_map(PCMachineState *pcms,
> MemoryRegion *rom_memory)
> {
> X86MachineState *x86ms = X86_MACHINE(pcms);
> + PCMachineClass *pcmc = PC_MACHINE_GET_CLASS(pcms);
> hwaddr total_size = 0;
> int i;
> BlockBackend *blk;
> @@ -184,7 +185,12 @@ static void pc_system_flash_map(PCMachineState *pcms,
>
> if (i == 0) {
> flash_mem = pflash_cfi01_get_memory(system_flash);
> - pc_isa_bios_init(&x86ms->isa_bios, rom_memory, flash_mem);
> + if (pcmc->isa_bios_alias) {
> + x86_isa_bios_init(&x86ms->isa_bios, rom_memory, flash_mem,
> + true);
> + } else {
> + pc_isa_bios_init(&x86ms->isa_bios, rom_memory, flash_mem);
> + }
>
> /* Encrypt the pflash boot ROM */
> if (sev_enabled()) {
> --
> 2.45.0
next prev parent reply other threads:[~2024-05-21 7:43 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-08 17:55 [PATCH v3 0/6] X86: Alias isa-bios area and clean up Bernhard Beschow
2024-05-08 17:55 ` [PATCH v3 1/6] hw/i386/x86: Eliminate two if statements in x86_bios_rom_init() Bernhard Beschow
2024-05-08 17:55 ` [PATCH v3 2/6] hw/i386: Have x86_bios_rom_init() take X86MachineState rather than MachineState Bernhard Beschow
2024-05-08 17:55 ` [PATCH v3 3/6] hw/i386/x86: Don't leak "isa-bios" memory regions Bernhard Beschow
2024-05-08 17:55 ` [PATCH v3 4/6] hw/i386/x86: Don't leak "pc.bios" memory region Bernhard Beschow
2024-05-08 17:55 ` [PATCH v3 5/6] hw/i386/x86: Extract x86_isa_bios_init() from x86_bios_rom_init() Bernhard Beschow
2024-05-08 17:55 ` [PATCH v3 6/6] hw/i386/pc_sysfw: Alias rather than copy isa-bios region Bernhard Beschow
2024-05-21 7:10 ` Bernhard Beschow
2024-05-21 7:13 ` Paolo Bonzini
2024-05-21 7:42 ` Michael S. Tsirkin [this message]
2024-05-08 20:39 ` [PATCH v3 0/6] X86: Alias isa-bios area and clean up BALATON Zoltan
2024-05-14 8:31 ` Bernhard Beschow
2024-05-08 22:10 ` Philippe Mathieu-Daudé
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