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Peter Anvin" To: Anthony Yznaga , 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 User-Agent: K-9 Mail for Android In-Reply-To: <1682554137-13938-22-git-send-email-anthony.yznaga@oracle.com> References: <1682554137-13938-1-git-send-email-anthony.yznaga@oracle.com> <1682554137-13938-22-git-send-email-anthony.yznaga@oracle.com> Message-ID: <70EB1774-A782-47FB-A8EA-534E66A551F6@zytor.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Queue-Id: 3DB751C0004 X-Rspamd-Server: rspam01 X-Stat-Signature: tsxwfjj741nb3qoxfwtqoerm5kpund4o X-HE-Tag: 1682620901-605852 X-HE-Meta: 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 eU8ll+QD Xv5w4gx02iMWS+iYEvmNu3Cl6vL7fJxTFTUlP7JsAWD7JC3Ja1bIgVF6SEACnUW/wA/SgkgGEFkMWM0DEhz1D+syBpCW3sKEtk9uMJHJkAgI7BI198xI7hrXidE/lQCgiLFowHoSzQDaxWeebb4pGF4ePiSHFgezNDwhHL4r+/CzWeDc4fMLAlUlZzpgxL5q6S8GRP9/h3CQvFOo= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On April 26, 2023 5:08:57 PM PDT, Anthony Yznaga wrote: >pkram kaslr code can incur multiple page faults when it walks its >preserved ranges list called via mem_avoid_overlap()=2E The multiple >faults can easily end up using up the small number of pages available >to be allocated for page table pages=2E > >This patch hacks things so that mappings are 1GB which results in the nee= d >for far fewer page table pages=2E As is this breaks AMD SEV-ES which exp= ects >the mappings to be 2M=2E This could possibly be fixed by updating split >code to split 1GB page if the aren't any other issues with using 1GB >mappings=2E > >Signed-off-by: Anthony Yznaga >--- > arch/x86/boot/compressed/ident_map_64=2Ec | 9 +++++---- > 1 file changed, 5 insertions(+), 4 deletions(-) > >diff --git a/arch/x86/boot/compressed/ident_map_64=2Ec b/arch/x86/boot/co= mpressed/ident_map_64=2Ec >index 321a5011042d=2E=2E1e02cf6dda3c 100644 >--- a/arch/x86/boot/compressed/ident_map_64=2Ec >+++ b/arch/x86/boot/compressed/ident_map_64=2Ec >@@ -95,8 +95,8 @@ void kernel_add_identity_map(unsigned long start, unsig= ned long end) > int ret; >=20 > /* Align boundary to 2M=2E */ >- start =3D round_down(start, PMD_SIZE); >- end =3D round_up(end, PMD_SIZE); >+ start =3D round_down(start, PUD_SIZE); >+ end =3D round_up(end, PUD_SIZE); > if (start >=3D end) > return; >=20 >@@ -120,6 +120,7 @@ void initialize_identity_maps(void *rmode) > mapping_info=2Econtext =3D &pgt_data; > mapping_info=2Epage_flag =3D __PAGE_KERNEL_LARGE_EXEC | sme_me_mask; > mapping_info=2Ekernpg_flag =3D _KERNPG_TABLE; >+ mapping_info=2Edirect_gbpages =3D true; >=20 > /* > * It should be impossible for this not to already be true, >@@ -365,8 +366,8 @@ void do_boot_page_fault(struct pt_regs *regs, unsigne= d long error_code) >=20 > ghcb_fault =3D sev_es_check_ghcb_fault(address); >=20 >- address &=3D PMD_MASK; >- end =3D address + PMD_SIZE; >+ address &=3D PUD_MASK; >+ end =3D address + PUD_SIZE; >=20 > /* > * Check for unexpected error codes=2E Unexpected are: Strong NAK: 1G pages are not supported by all 64-bit CPUs, *and* by your o= wn admission breaks things =2E=2E=2E