From: Dave Hansen <dave.hansen@intel.com>
To: Joerg Roedel <joro@8bytes.org>, 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: Re: [PATCH v2 3/4] x86/mm: Flush global TLB when switching to trampoline page-table
Date: Wed, 29 Sep 2021 08:07:10 -0700 [thread overview]
Message-ID: <18be825f-b3f3-3e05-1b14-82712d9a6c0d@intel.com> (raw)
In-Reply-To: <20210929145501.4612-4-joro@8bytes.org>
On 9/29/21 7:55 AM, Joerg Roedel wrote:
> + /*
> + * Flush global TLB entries to catch any bugs where code running on the
> + * trampoline_pgd uses memory not mapped into the trampoline page-table.
> + */
> + __flush_tlb_all();
> +}
This comment took me a minute to parse. How about a bit more info, like:
/*
* The CR3 writes above may not flush global TLB entries.
* Stale, global entries from previous sets of 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.
*/
next prev parent reply other threads:[~2021-09-29 15:07 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-29 14:54 [PATCH v2 0/4] x86/mm: Fix some issues with using trampoline_pgd Joerg Roedel
2021-09-29 14:54 ` [PATCH v2 1/4] x86/realmode: Add comment for Global bit usage in trampline_pgd Joerg Roedel
2021-09-29 14:54 ` [PATCH v2 2/4] x86/mm/64: Flush global TLB on AP bringup Joerg Roedel
2021-09-29 15:09 ` Dave Hansen
2021-09-30 13:52 ` Joerg Roedel
2021-09-29 14:55 ` [PATCH v2 3/4] x86/mm: Flush global TLB when switching to trampoline page-table Joerg Roedel
2021-09-29 15:07 ` Dave Hansen [this message]
2021-10-01 12:37 ` Joerg Roedel
2021-09-29 14:55 ` [PATCH v2 4/4] x86/64/mm: Map all kernel memory into trampoline_pgd Joerg Roedel
2021-09-29 15:22 ` Dave Hansen
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