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Message-ID: <CAMj1kXFoNTe3bPg6XHydJk8izcTrofEhH7Wpar1VwgpboEobmw@mail.gmail.com>
Date: Tue, 16 May 2023 19:25:51 +0200
From: Ard Biesheuvel <ardb@...nel.org>
To: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Cc: aarcange@...hat.com, ak@...ux.intel.com, akpm@...ux-foundation.org,
bp@...en8.de, dave.hansen@...el.com, david@...hat.com,
dfaggioli@...e.com, jroedel@...e.de, khalid.elmously@...onical.com,
linux-coco@...ts.linux.dev, linux-efi@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-mm@...ck.org, luto@...nel.org,
marcelo.cerri@...onical.com, mgorman@...hsingularity.net,
mingo@...hat.com, pbonzini@...hat.com, peterx@...hat.com,
peterz@...radead.org, philip.cox@...onical.com,
rientjes@...gle.com, rppt@...nel.org,
sathyanarayanan.kuppuswamy@...ux.intel.com, seanjc@...gle.com,
tglx@...utronix.de, thomas.lendacky@....com,
tim.gardner@...onical.com, vbabka@...e.cz, x86@...nel.org
Subject: Re: [PATCHv11.1 5/9] efi: Add unaccepted memory support
On Tue, 16 May 2023 at 14:07, Kirill A. Shutemov
<kirill.shutemov@...ux.intel.com> wrote:
>
> efi_config_parse_tables() reserves memory that holds unaccepted memory
> configuration table so it won't be reused by page allocator.
>
> Core-mm requires few helpers to support unaccepted memory:
>
> - accept_memory() checks the range of addresses against the bitmap and
> accept memory if needed.
>
> - range_contains_unaccepted_memory() checks if anything within the
> range requires acceptance.
>
> Architectural code has to provide efi_get_unaccepted_table() that
> returns pointer to the unaccepted memory configuration table.
>
> arch_accept_memory() handles arch-specific part of memory acceptance.
>
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
>
Reviewed-by: Ard Biesheuvel <ardb@...nel.org>
> v11.1:
> - Add missing memblock_reserve() for the unaccepted memory
> configuration table.
>
> ---
> drivers/firmware/efi/Makefile | 1 +
> drivers/firmware/efi/efi.c | 25 ++++++
> drivers/firmware/efi/unaccepted_memory.c | 103 +++++++++++++++++++++++
> include/linux/efi.h | 1 +
> 4 files changed, 130 insertions(+)
> create mode 100644 drivers/firmware/efi/unaccepted_memory.c
>
> diff --git a/drivers/firmware/efi/Makefile b/drivers/firmware/efi/Makefile
> index b51f2a4c821e..e489fefd23da 100644
> --- a/drivers/firmware/efi/Makefile
> +++ b/drivers/firmware/efi/Makefile
> @@ -41,3 +41,4 @@ obj-$(CONFIG_EFI_CAPSULE_LOADER) += capsule-loader.o
> obj-$(CONFIG_EFI_EARLYCON) += earlycon.o
> obj-$(CONFIG_UEFI_CPER_ARM) += cper-arm.o
> obj-$(CONFIG_UEFI_CPER_X86) += cper-x86.o
> +obj-$(CONFIG_UNACCEPTED_MEMORY) += unaccepted_memory.o
> diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
> index 7dce06e419c5..d817e7afd266 100644
> --- a/drivers/firmware/efi/efi.c
> +++ b/drivers/firmware/efi/efi.c
> @@ -50,6 +50,9 @@ struct efi __read_mostly efi = {
> #ifdef CONFIG_EFI_COCO_SECRET
> .coco_secret = EFI_INVALID_TABLE_ADDR,
> #endif
> +#ifdef CONFIG_UNACCEPTED_MEMORY
> + .unaccepted = EFI_INVALID_TABLE_ADDR,
> +#endif
> };
> EXPORT_SYMBOL(efi);
>
> @@ -605,6 +608,9 @@ static const efi_config_table_type_t common_tables[] __initconst = {
> #ifdef CONFIG_EFI_COCO_SECRET
> {LINUX_EFI_COCO_SECRET_AREA_GUID, &efi.coco_secret, "CocoSecret" },
> #endif
> +#ifdef CONFIG_UNACCEPTED_MEMORY
> + {LINUX_EFI_UNACCEPTED_MEM_TABLE_GUID, &efi.unaccepted, "Unaccepted" },
> +#endif
> #ifdef CONFIG_EFI_GENERIC_STUB
> {LINUX_EFI_SCREEN_INFO_TABLE_GUID, &screen_info_table },
> #endif
> @@ -759,6 +765,25 @@ int __init efi_config_parse_tables(const efi_config_table_t *config_tables,
> }
> }
>
> + if (IS_ENABLED(CONFIG_UNACCEPTED_MEMORY) &&
> + efi.unaccepted != EFI_INVALID_TABLE_ADDR) {
> + struct efi_unaccepted_memory *unaccepted;
> +
> + unaccepted = early_memremap(efi.unaccepted, sizeof(*unaccepted));
> + if (unaccepted) {
> + unsigned long size;
> +
> + if (unaccepted->version == 1) {
> + size = sizeof(*unaccepted) + unaccepted->size;
> + memblock_reserve(efi.unaccepted, size);
> + } else {
> + efi.unaccepted = EFI_INVALID_TABLE_ADDR;
> + }
> +
> + early_memunmap(unaccepted, sizeof(*unaccepted));
> + }
> + }
> +
> return 0;
> }
>
> diff --git a/drivers/firmware/efi/unaccepted_memory.c b/drivers/firmware/efi/unaccepted_memory.c
> new file mode 100644
> index 000000000000..bb91c41f76fb
> --- /dev/null
> +++ b/drivers/firmware/efi/unaccepted_memory.c
> @@ -0,0 +1,103 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +
> +#include <linux/efi.h>
> +#include <linux/memblock.h>
> +#include <linux/spinlock.h>
> +#include <asm/unaccepted_memory.h>
> +
> +/* Protects unaccepted memory bitmap */
> +static DEFINE_SPINLOCK(unaccepted_memory_lock);
> +
> +void accept_memory(phys_addr_t start, phys_addr_t end)
> +{
> + struct efi_unaccepted_memory *unaccepted;
> + unsigned long range_start, range_end;
> + unsigned long flags;
> + u64 unit_size;
> +
> + if (efi.unaccepted == EFI_INVALID_TABLE_ADDR)
> + return;
> +
> + unaccepted = efi_get_unaccepted_table();
> + if (!unaccepted)
> + return;
> +
> + unit_size = unaccepted->unit_size;
> +
> + /*
> + * Only care for the part of the range that is represented
> + * in the bitmap.
> + */
> + if (start < unaccepted->phys_base)
> + start = unaccepted->phys_base;
> + if (end < unaccepted->phys_base)
> + return;
> +
> + /* Translate to offsets from the beginning of the bitmap */
> + start -= unaccepted->phys_base;
> + end -= unaccepted->phys_base;
> +
> + /* Make sure not to overrun the bitmap */
> + if (end > unaccepted->size * unit_size * BITS_PER_BYTE)
> + end = unaccepted->size * unit_size * BITS_PER_BYTE;
> +
> + range_start = start / unit_size;
> +
> + spin_lock_irqsave(&unaccepted_memory_lock, flags);
> + for_each_set_bitrange_from(range_start, range_end, unaccepted->bitmap,
> + DIV_ROUND_UP(end, unit_size)) {
> + unsigned long phys_start, phys_end;
> + unsigned long len = range_end - range_start;
> +
> + phys_start = range_start * unit_size + unaccepted->phys_base;
> + phys_end = range_end * unit_size + unaccepted->phys_base;
> +
> + arch_accept_memory(phys_start, phys_end);
> + bitmap_clear(unaccepted->bitmap, range_start, len);
> + }
> + spin_unlock_irqrestore(&unaccepted_memory_lock, flags);
> +}
> +
> +bool range_contains_unaccepted_memory(phys_addr_t start, phys_addr_t end)
> +{
> + struct efi_unaccepted_memory *unaccepted;
> + unsigned long flags;
> + bool ret = false;
> + u64 unit_size;
> +
> + unaccepted = efi_get_unaccepted_table();
> + if (!unaccepted)
> + return false;
> +
> + unit_size = unaccepted->unit_size;
> +
> + /*
> + * Only care for the part of the range that is represented
> + * in the bitmap.
> + */
> + if (start < unaccepted->phys_base)
> + start = unaccepted->phys_base;
> + if (end < unaccepted->phys_base)
> + return false;
> +
> + /* Translate to offsets from the beginning of the bitmap */
> + start -= unaccepted->phys_base;
> + end -= unaccepted->phys_base;
> +
> + /* Make sure not to overrun the bitmap */
> + if (end > unaccepted->size * unit_size * BITS_PER_BYTE)
> + end = unaccepted->size * unit_size * BITS_PER_BYTE;
> +
> + spin_lock_irqsave(&unaccepted_memory_lock, flags);
> + while (start < end) {
> + if (test_bit(start / unit_size, unaccepted->bitmap)) {
> + ret = true;
> + break;
> + }
> +
> + start += unit_size;
> + }
> + spin_unlock_irqrestore(&unaccepted_memory_lock, flags);
> +
> + return ret;
> +}
> diff --git a/include/linux/efi.h b/include/linux/efi.h
> index 29cc622910da..9864f9c00da2 100644
> --- a/include/linux/efi.h
> +++ b/include/linux/efi.h
> @@ -646,6 +646,7 @@ extern struct efi {
> unsigned long tpm_final_log; /* TPM2 Final Events Log table */
> unsigned long mokvar_table; /* MOK variable config table */
> unsigned long coco_secret; /* Confidential computing secret table */
> + unsigned long unaccepted; /* Unaccepted memory table */
>
> efi_get_time_t *get_time;
> efi_set_time_t *set_time;
> --
> 2.39.3
>
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