From: "H. Peter Anvin" <hpa@zytor.com>
To: Anthony Yznaga <anthony.yznaga@oracle.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Cc: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de,
x86@kernel.org, dave.hansen@linux.intel.com, luto@kernel.org,
peterz@infradead.org, rppt@kernel.org, akpm@linux-foundation.org,
ebiederm@xmission.com, keescook@chromium.org, graf@amazon.com,
jason.zeng@intel.com, lei.l.li@intel.com,
steven.sistare@oracle.com, fam.zheng@bytedance.com,
mgalaxy@akamai.com, kexec@lists.infradead.org
Subject: Re: [RFC v3 21/21] x86/boot/compressed/64: use 1GB pages for mappings
Date: Thu, 27 Apr 2023 11:40:02 -0700 [thread overview]
Message-ID: <70EB1774-A782-47FB-A8EA-534E66A551F6@zytor.com> (raw)
In-Reply-To: <1682554137-13938-22-git-send-email-anthony.yznaga@oracle.com>
On April 26, 2023 5:08:57 PM PDT, Anthony Yznaga <anthony.yznaga@oracle.com> wrote:
>pkram kaslr code can incur multiple page faults when it walks its
>preserved ranges list called via mem_avoid_overlap(). The multiple
>faults can easily end up using up the small number of pages available
>to be allocated for page table pages.
>
>This patch hacks things so that mappings are 1GB which results in the need
>for far fewer page table pages. As is this breaks AMD SEV-ES which expects
>the mappings to be 2M. This could possibly be fixed by updating split
>code to split 1GB page if the aren't any other issues with using 1GB
>mappings.
>
>Signed-off-by: Anthony Yznaga <anthony.yznaga@oracle.com>
>---
> arch/x86/boot/compressed/ident_map_64.c | 9 +++++----
> 1 file changed, 5 insertions(+), 4 deletions(-)
>
>diff --git a/arch/x86/boot/compressed/ident_map_64.c b/arch/x86/boot/compressed/ident_map_64.c
>index 321a5011042d..1e02cf6dda3c 100644
>--- a/arch/x86/boot/compressed/ident_map_64.c
>+++ b/arch/x86/boot/compressed/ident_map_64.c
>@@ -95,8 +95,8 @@ void kernel_add_identity_map(unsigned long start, unsigned long end)
> int ret;
>
> /* Align boundary to 2M. */
>- start = round_down(start, PMD_SIZE);
>- end = round_up(end, PMD_SIZE);
>+ start = round_down(start, PUD_SIZE);
>+ end = round_up(end, PUD_SIZE);
> if (start >= end)
> return;
>
>@@ -120,6 +120,7 @@ void initialize_identity_maps(void *rmode)
> mapping_info.context = &pgt_data;
> mapping_info.page_flag = __PAGE_KERNEL_LARGE_EXEC | sme_me_mask;
> mapping_info.kernpg_flag = _KERNPG_TABLE;
>+ mapping_info.direct_gbpages = true;
>
> /*
> * It should be impossible for this not to already be true,
>@@ -365,8 +366,8 @@ void do_boot_page_fault(struct pt_regs *regs, unsigned long error_code)
>
> ghcb_fault = sev_es_check_ghcb_fault(address);
>
>- address &= PMD_MASK;
>- end = address + PMD_SIZE;
>+ address &= PUD_MASK;
>+ end = address + PUD_SIZE;
>
> /*
> * Check for unexpected error codes. Unexpected are:
Strong NAK: 1G pages are not supported by all 64-bit CPUs, *and* by your own admission breaks things ...
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next prev parent reply other threads:[~2023-04-27 18:42 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-27 0:08 [RFC v3 00/21] Preserved-over-Kexec RAM Anthony Yznaga
2023-04-27 0:08 ` [RFC v3 01/21] mm: add PKRAM API stubs and Kconfig Anthony Yznaga
2023-04-27 0:08 ` [RFC v3 02/21] mm: PKRAM: implement node load and save functions Anthony Yznaga
2023-04-27 0:08 ` [RFC v3 03/21] mm: PKRAM: implement object " Anthony Yznaga
2023-04-27 0:08 ` [RFC v3 04/21] mm: PKRAM: implement folio stream operations Anthony Yznaga
2023-04-27 0:08 ` [RFC v3 05/21] mm: PKRAM: implement byte " Anthony Yznaga
2023-04-27 0:08 ` [RFC v3 06/21] mm: PKRAM: link nodes by pfn before reboot Anthony Yznaga
2023-04-27 0:08 ` [RFC v3 07/21] mm: PKRAM: introduce super block Anthony Yznaga
2023-06-05 2:40 ` Coiby Xu
2023-06-06 2:01 ` Anthony Yznaga
2023-06-06 2:55 ` Coiby Xu
2023-06-06 3:12 ` Anthony Yznaga
2023-04-27 0:08 ` [RFC v3 08/21] PKRAM: track preserved pages in a physical mapping pagetable Anthony Yznaga
2023-04-27 0:08 ` [RFC v3 09/21] PKRAM: pass a list of preserved ranges to the next kernel Anthony Yznaga
2023-04-27 0:08 ` [RFC v3 10/21] PKRAM: prepare for adding preserved ranges to memblock reserved Anthony Yznaga
2023-04-27 0:08 ` [RFC v3 11/21] mm: PKRAM: reserve preserved memory at boot Anthony Yznaga
2023-04-27 0:08 ` [RFC v3 12/21] PKRAM: free the preserved ranges list Anthony Yznaga
2023-04-27 0:08 ` [RFC v3 13/21] PKRAM: prevent inadvertent use of a stale superblock Anthony Yznaga
2023-04-27 0:08 ` [RFC v3 14/21] PKRAM: provide a way to ban pages from use by PKRAM Anthony Yznaga
2023-04-27 0:08 ` [RFC v3 15/21] kexec: PKRAM: prevent kexec clobbering preserved pages in some cases Anthony Yznaga
2023-04-27 0:08 ` [RFC v3 16/21] PKRAM: provide a way to check if a memory range has preserved pages Anthony Yznaga
2023-04-27 0:08 ` [RFC v3 17/21] kexec: PKRAM: avoid clobbering already " Anthony Yznaga
2023-04-27 0:08 ` [RFC v3 18/21] mm: PKRAM: allow preserved memory to be freed from userspace Anthony Yznaga
2023-04-27 0:08 ` [RFC v3 19/21] PKRAM: disable feature when running the kdump kernel Anthony Yznaga
2023-04-27 0:08 ` [RFC v3 20/21] x86/KASLR: PKRAM: support physical kaslr Anthony Yznaga
2023-04-27 0:08 ` [RFC v3 21/21] x86/boot/compressed/64: use 1GB pages for mappings Anthony Yznaga
2023-04-27 18:40 ` H. Peter Anvin [this message]
2023-04-27 22:38 ` Anthony Yznaga
2023-05-26 13:57 ` [RFC v3 00/21] Preserved-over-Kexec RAM Gowans, James
2023-05-31 23:14 ` Anthony Yznaga
2023-06-01 2:15 ` Baoquan He
2023-06-01 23:58 ` Anthony Yznaga
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