Messages in this thread | | | From | Joerg Roedel <> | Subject | [PATCH v4 0/4] x86/mm: Fix some issues with using trampoline_pgd | Date | Thu, 2 Dec 2021 16:32:22 +0100 |
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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
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