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;
MIME-Version: 1.0
References: <20220607093805.1354256-1-mawupeng1@huawei.com> <CAMj1kXH5r=CUoLCndBUsZ04_0UCJ2VqgJDdp2wbdNCtEx0Yxag@mail.gmail.com>
In-Reply-To: <CAMj1kXH5r=CUoLCndBUsZ04_0UCJ2VqgJDdp2wbdNCtEx0Yxag@mail.gmail.com>
From:   Ard Biesheuvel <ardb@kernel.org>
Date:   Fri, 10 Jun 2022 13:24:48 +0200
Message-ID: <CAMj1kXHNK+t1yWMP4+syi-_01qxZ=o-5HoaTTzRhFM7EqLaBPQ@mail.gmail.com>
Subject: Re: [PATCH v3 0/6] introduce mirrored memory support for arm64
To:     Wupeng Ma <mawupeng1@huawei.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Mike Rapoport <rppt@kernel.org>
Cc:     Jonathan Corbet <corbet@lwn.net>, Will Deacon <will@kernel.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        X86 ML <x86@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>,
        Darren Hart <dvhart@infradead.org>,
        Andy Shevchenko <andy@infradead.org>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        "Paul E. McKenney" <paulmck@kernel.org>,
        Kees Cook <keescook@chromium.org>, songmuchun@bytedance.com,
        Randy Dunlap <rdunlap@infradead.org>,
        damien.lemoal@opensource.wdc.com,
        Stephen Boyd <swboyd@chromium.org>,
        Wei Liu <wei.liu@kernel.org>,
        Robin Murphy <robin.murphy@arm.com>,
        David Hildenbrand <david@redhat.com>,
        Anshuman Khandual <anshuman.khandual@arm.com>,
        Zhen Lei <thunder.leizhen@huawei.com>,
        Kefeng Wang <wangkefeng.wang@huawei.com>, gpiccoli@igalia.com,
        Huacai Chen <chenhuacai@kernel.org>,
        Geert Uytterhoeven <geert@linux-m68k.org>,
        chenzhou10@huawei.com, vijayb@linux.microsoft.com,
        Linux Doc Mailing List <linux-doc@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        linux-efi@vger.kernel.org, platform-driver-x86@vger.kernel.org,
        linux-mm@kvack.org, linux-riscv@lists.infradead.org
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Fri, 10 Jun 2022 at 13:23, Ard Biesheuvel <ardb@kernel.org> wrote:
>
> On Tue, 7 Jun 2022 at 11:16, Wupeng Ma <mawupeng1@huawei.com> wrote:
> >
> > From: Ma Wupeng <mawupeng1@huawei.com>
> >
> > Commit b05b9f5f9dcf ("x86, mirror: x86 enabling - find mirrored memory ranges")
> > introduced mirrored memory support for x86. This support rely on UEFI to
> > report mirrored memory address ranges.  See UEFI 2.5 spec pages 157-158:
> >
> >   http://www.uefi.org/sites/default/files/resources/UEFI%202_5.pdf
> >
> > Memory mirroring is a technique used to separate memory into two separate
> > channels, usually on a memory device, like a server. In memory mirroring,
> > one channel is copied to another to create redundancy. This method makes
> > input/output (I/O) registers and memory appear with more than one address
> > range because the same physical byte is accessible at more than one
> > address. Using memory mirroring, higher memory reliability and a higher
> > level of memory consolidation are possible.
> >
> > These EFI memory regions have various attributes, and the "mirrored"
> > attribute is one of them. The physical memory region whose descriptors
> > in EFI memory map has EFI_MEMORY_MORE_RELIABLE attribute (bit: 16) are
> > mirrored. The address range mirroring feature of the kernel arranges such
> > mirrored regions into normal zones and other regions into movable zones.
> >
> > Arm64 can support this too. So mirrored memory support is added to support
> > arm64.
> >
> > The main purpose of this patch set is to introduce mirrored support for
> > arm64 and we have already fixed the problems we had which is shown in
> > patch #5 to patch #8 and try to bring total isolation in patch #9 which
> > will disable mirror feature if kernelcore is not specified.
> >
> > In order to test this support in arm64:
> > - patch this patch set
> > - add kernelcore=mirror in kernel parameter
> > - start you kernel
> >
> > Patch #1-#2 introduce mirrored memory support form arm64.
> > Patch #3-#5 fix some bugs for arm64 if memory reliable is enabled.
> > Patch #6 disable mirror feature if kernelcore is not specified.
> >
> > Thanks to Ard Biesheuvel's hard work [1], now kernel will perfer mirrored
> > memory if kaslr is enabled.
> >
> > [1] https://lore.kernel.org/linux-arm-kernel/CAMj1kXEPVEzMgOM4+Yj6PxHA-jFuDOAUdDJSiSxy_XaP4P7LSw@mail.gmail.com/T/
> >
> > Changelog since v2:
> > - remove efi_fake_mem support
> > - remove Commit ("remove some redundant code in ia64 efi_init") since
> >   efi_print_memmap() is not public
> > - add mirror flag back on initrd memory
> >
> > Changelog since v1:
> > - update changelog in cover letter
> > - use PHYS_PFN in patch #7
> >
> > Ma Wupeng (6):
> >   efi: Make efi_find_mirror() public
> >   arm64/mirror: arm64 enabling - find mirrored memory ranges
> >   mm: Ratelimited mirrored memory related warning messages
> >   mm: Demote warning message in vmemmap_verify() to debug level
> >   mm: Add mirror flag back on initrd memory
> >   efi: Disable mirror feature if kernelcore is not specified
> >
>
> I have tested these changes on QEMU/arm64 with the patch below, and
> things seem to work as expected. We have some minor issues to work out
> but the general shape of this code is good.
>
> As for the mm/ changes: does anyone mind if I take those through the
> EFI tree as well? I don't think the EFI and -mm changes depend on each
> other, so they can go into -mm separately as well.

diff --git a/drivers/firmware/efi/libstub/efi-stub.c
b/drivers/firmware/efi/libstub/efi-stub.c
index f515394cce6e..1d4dd8aca3e6 100644
--- a/drivers/firmware/efi/libstub/efi-stub.c
+++ b/drivers/firmware/efi/libstub/efi-stub.c
@@ -136,6 +136,7 @@ efi_status_t __efiapi efi_pe_entry(efi_handle_t handle,
        enum efi_secureboot_mode secure_boot;
        struct screen_info *si;
        efi_properties_table_t *prop_tbl;
+       const efi_dxe_services_table_t *efi_dxe_table;

        efi_system_table = sys_table_arg;

@@ -161,6 +162,20 @@ efi_status_t __efiapi efi_pe_entry(efi_handle_t handle,
                goto fail;
        }

+       efi_dxe_table = get_efi_config_table(EFI_DXE_SERVICES_TABLE_GUID);
+       if (efi_dxe_table) {
+               efi_physical_addr_t pa = 0x60000000;
+               efi_gcd_memory_space_desc_t desc;
+
+               status = efi_dxe_call(get_memory_space_descriptor, pa, &desc);
+               if (status != EFI_SUCCESS)
+                       efi_err("Failed to get memory space
descriptor: %lx\n", status);
+               status = efi_dxe_call(set_memory_space_capabilities, pa, SZ_1G,
+                                     desc.capabilities |
EFI_MEMORY_MORE_RELIABLE);
+               if (status != EFI_SUCCESS)
+                       efi_err("Failed to set memory space
capabilities: %lx\n", status);
+       }
+
        /*
         * Get the command line from EFI, using the LOADED_IMAGE
         * protocol. We are going to copy the command line into the
diff --git a/drivers/firmware/efi/libstub/efistub.h
b/drivers/firmware/efi/libstub/efistub.h
index b0ae0a454404..bf11d85bf9b4 100644
--- a/drivers/firmware/efi/libstub/efistub.h
+++ b/drivers/firmware/efi/libstub/efistub.h
@@ -378,7 +378,8 @@ union efi_dxe_services_table {
                void *schedule;
                void *trust;
                void *process_firmware_volume;
-               void *set_memory_space_capabilities;
+               efi_status_t (__efiapi
*set_memory_space_capabilities)(efi_physical_addr_t,
+
u64, u64);
        };
        struct {
                efi_table_hdr_t hdr;