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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>,
	Mike Rapoport <rppt@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Brijesh Singh <brijesh.singh@amd.com>,
	linux-kernel@vger.kernel.org, Joerg Roedel <jroedel@suse.de>,
	Joerg Roedel <joro@8bytes.org>
Subject: [PATCH v4 0/4] x86/mm: Fix some issues with using trampoline_pgd
Date: Thu,  2 Dec 2021 16:32:22 +0100	[thread overview]
Message-ID: <20211202153226.22946-1-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 v3->v4:

	- Rebased to latest tip/master
	- Addressed Boris' review comments

Link to v3: https://lore.kernel.org/all/20211001154817.29225-1-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/include/asm/tlbflush.h |  5 +++++
 arch/x86/kernel/head64.c        |  2 ++
 arch/x86/kernel/head_64.S       | 19 ++++++++++++++++-
 arch/x86/kernel/reboot.c        | 12 ++---------
 arch/x86/mm/init.c              |  5 +++++
 arch/x86/mm/tlb.c               |  8 ++-----
 arch/x86/realmode/init.c        | 38 ++++++++++++++++++++++++++++++++-
 8 files changed, 72 insertions(+), 18 deletions(-)


base-commit: b6c28e3cc445bf451a516ac075ec27b4619e4f5f
-- 
2.34.0


             reply	other threads:[~2021-12-02 15:33 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-12-02 15:32 Joerg Roedel [this message]
2021-12-02 15:32 ` [PATCH v4 1/4] x86/realmode: Add comment for Global bit usage in trampline_pgd Joerg Roedel
2021-12-06 21:57   ` [tip: x86/mm] x86/realmode: Add comment for Global bit usage in trampoline_pgd tip-bot2 for Joerg Roedel
2021-12-02 15:32 ` [PATCH v4 2/4] x86/mm/64: Flush global TLB on boot and AP bringup Joerg Roedel
2021-12-06 21:57   ` [tip: x86/mm] " tip-bot2 for Joerg Roedel
2021-12-02 15:32 ` [PATCH v4 3/4] x86/mm: Flush global TLB when switching to trampoline page-table Joerg Roedel
2021-12-06 21:57   ` [tip: x86/mm] " tip-bot2 for Joerg Roedel
2021-12-02 15:32 ` [PATCH v4 4/4] x86/64/mm: Map all kernel memory into trampoline_pgd Joerg Roedel
2021-12-03 10:04   ` [tip: x86/urgent] " tip-bot2 for Joerg Roedel

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