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From: Joerg Roedel <joro@8bytes.org>
To: x86@kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	hpa@zytor.com, Dave Hansen <dave.hansen@linux.intel.com>,
	Andy Lutomirski <luto@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Joerg Roedel <jroedel@suse.de>, Mike Rapoport <rppt@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Brijesh Singh <brijesh.singh@amd.com>,
	linux-kernel@vger.kernel.org
Subject: [PATCH v3 0/4] x86/mm: Fix some issues with using trampoline_pgd
Date: Fri,  1 Oct 2021 17:48:13 +0200	[thread overview]
Message-ID: <20211001154817.29225-1-joro@8bytes.org> (raw)

From: Joerg Roedel <jroedel@suse.de>

Hi,

here are a couple of fixes and documentation improvements for the use
of the trampoline_pgd in the kernel. Most importantly it fixes the
issue that switching to the trampoline_pgd will unmap the kernel stack
and real_mode_header, making crashes likely before the code can
actually jump to real mode.

The first patch adds a comment to document that the trampoline_pgd
aliases kernel page-tables in the user address range, establishing
global TLB entries for these addresses. The next two patches add
global TLB flushes when switching to and from the trampoline_pgd.

The last patch extends the trampoline_pgd to cover the whole kernel
address range. This is needed to make sure the stack and the
real_mode_header are still mapped after the switch and that the code
flow can safely reach real-mode.

Please review.

Thanks,

	Joerg

Changes v2->v3:

	- Addressed review comments from Dave Hansen

Link to v2: https://lore.kernel.org/lkml/20210929145501.4612-1-joro@8bytes.org/

Joerg Roedel (4):
  x86/realmode: Add comment for Global bit usage in trampline_pgd
  x86/mm/64: Flush global TLB on boot and AP bringup
  x86/mm: Flush global TLB when switching to trampoline page-table
  x86/64/mm: Map all kernel memory into trampoline_pgd

 arch/x86/include/asm/realmode.h |  1 +
 arch/x86/kernel/head64.c        | 15 ++++++++++++++
 arch/x86/kernel/head_64.S       | 19 +++++++++++++++++-
 arch/x86/kernel/reboot.c        | 12 ++---------
 arch/x86/mm/init.c              |  5 +++++
 arch/x86/realmode/init.c        | 35 ++++++++++++++++++++++++++++++++-
 6 files changed, 75 insertions(+), 12 deletions(-)


base-commit: 5816b3e6577eaa676ceb00a848f0fd65fe2adc29
-- 
2.33.0


             reply	other threads:[~2021-10-01 15:48 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-01 15:48 Joerg Roedel [this message]
2021-10-01 15:48 ` [PATCH v3 1/4] x86/realmode: Add comment for Global bit usage in trampline_pgd Joerg Roedel
2021-10-01 15:48 ` [PATCH v3 2/4] x86/mm/64: Flush global TLB on boot and AP bringup Joerg Roedel
2021-10-26  9:55   ` Borislav Petkov
2021-10-26 12:58     ` Borislav Petkov
2021-12-02 12:50       ` Joerg Roedel
2021-12-02 18:19         ` Borislav Petkov
2021-12-02 21:17           ` Joerg Roedel
2021-10-01 15:48 ` [PATCH v3 3/4] x86/mm: Flush global TLB when switching to trampoline page-table Joerg Roedel
2021-10-01 16:13   ` Dave Hansen
2021-10-01 17:57     ` Jörg Rödel
2021-10-27  9:58   ` Borislav Petkov
2021-12-02 12:58     ` Joerg Roedel
2021-12-02 18:26       ` Borislav Petkov
2021-10-01 15:48 ` [PATCH v3 4/4] x86/64/mm: Map all kernel memory into trampoline_pgd Joerg Roedel

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