diff options
| author | Joerg Roedel <jroedel@suse.de> | 2021-12-02 16:32:25 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-01-27 09:19:42 +0100 |
| commit | ff867910e87c2c1613f2a879b47c71c9a447621e (patch) | |
| tree | c37349ff6047be5881d92a854f669e3b0652d8ae /arch/x86 | |
| parent | 16f2ef98cccfd2b26456581ae02ea875bc789e62 (diff) | |
x86/mm: Flush global TLB when switching to trampoline page-table
[ Upstream commit 71d5049b053876afbde6c3273250b76935494ab2 ]
Move the switching code into a function so that it can be re-used and
add a global TLB flush. This makes sure that usage of memory which is
not mapped in the trampoline page-table is reliably caught.
Also move the clearing of CR4.PCIDE before the CR3 switch because the
cr4_clear_bits() function will access data not mapped into the
trampoline page-table.
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20211202153226.22946-4-joro@8bytes.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/include/asm/realmode.h | 1 | ||||
| -rw-r--r-- | arch/x86/kernel/reboot.c | 12 | ||||
| -rw-r--r-- | arch/x86/realmode/init.c | 26 |
3 files changed, 29 insertions, 10 deletions
diff --git a/arch/x86/include/asm/realmode.h b/arch/x86/include/asm/realmode.h index 09ecc32f6524..52d7512ea91a 100644 --- a/arch/x86/include/asm/realmode.h +++ b/arch/x86/include/asm/realmode.h @@ -82,6 +82,7 @@ static inline void set_real_mode_mem(phys_addr_t mem) } void reserve_real_mode(void); +void load_trampoline_pgtable(void); #endif /* __ASSEMBLY__ */ diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c index d65d1afb2716..fdef27a84d71 100644 --- a/arch/x86/kernel/reboot.c +++ b/arch/x86/kernel/reboot.c @@ -113,17 +113,9 @@ void __noreturn machine_real_restart(unsigned int type) spin_unlock(&rtc_lock); /* - * Switch back to the initial page table. + * Switch to the trampoline page table. */ -#ifdef CONFIG_X86_32 - load_cr3(initial_page_table); -#else - write_cr3(real_mode_header->trampoline_pgd); - - /* Exiting long mode will fail if CR4.PCIDE is set. */ - if (boot_cpu_has(X86_FEATURE_PCID)) - cr4_clear_bits(X86_CR4_PCIDE); -#endif + load_trampoline_pgtable(); /* Jump to the identity-mapped low memory code */ #ifdef CONFIG_X86_32 diff --git a/arch/x86/realmode/init.c b/arch/x86/realmode/init.c index de371e52cfa8..fac50ebb122b 100644 --- a/arch/x86/realmode/init.c +++ b/arch/x86/realmode/init.c @@ -16,6 +16,32 @@ u32 *trampoline_cr4_features; /* Hold the pgd entry used on booting additional CPUs */ pgd_t trampoline_pgd_entry; +void load_trampoline_pgtable(void) +{ +#ifdef CONFIG_X86_32 + load_cr3(initial_page_table); +#else + /* + * This function is called before exiting to real-mode and that will + * fail with CR4.PCIDE still set. + */ + if (boot_cpu_has(X86_FEATURE_PCID)) + cr4_clear_bits(X86_CR4_PCIDE); + + write_cr3(real_mode_header->trampoline_pgd); +#endif + + /* + * The CR3 write above will not flush global TLB entries. + * Stale, global entries from previous page tables may still be + * present. Flush those stale entries. + * + * This ensures that memory accessed while running with + * trampoline_pgd is *actually* mapped into trampoline_pgd. + */ + __flush_tlb_all(); +} + void __init reserve_real_mode(void) { phys_addr_t mem; |