From: Pavel Tatashin <pasha.tatashin@soleen.com>
To: James Morse <james.morse@arm.com>
Cc: Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: [RFC PATCH 3/3] arm64: hibernate: idmap the single page that holds the copy page routines
Date: Fri, 20 Mar 2020 17:22:20 -0400 [thread overview]
Message-ID: <CA+CK2bAEyp7Kcc_qEOfchNvyEHSVnjAXD-LB9NGbUOJ_xZV1AQ@mail.gmail.com> (raw)
In-Reply-To: <20200115143322.214247-4-james.morse@arm.com>
Hi James,
Sorry, for a slow response.
Soon, I will send out updated MMU enabled kexec series which will have
this work included. I appreciate your help with this.
> Today the address it uses for this mapping is arbitrary, but to allow
> kexec to reuse this code, it needs to be idmapped. To idmap the page
> we must avoid the kernel helpers that have VA_BITS baked in.
Makes sense.
> Convert create_single_mapping() to take a single PA, and idmap it.
I like the idea of using idmap in both places!
> The page tables are built in the reverse order to normal using
> pfn_pte() to stir in any bits between 52:48. T0SZ is always increased
> to cover 48bits, or 52 if the copy code has bits 52:48 in its PA.
I do not think this will work for kexec case. In hibernate we map only
one page, so we can allocate every level from bottom to top, but in
kexec we map many pages. So, upper levels might already exist. I think
we will need to modify the loop to still go from top to bottom.
Otherwise, this work makes sense. I will integrate it into my series.
Thank you,
Pasha
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next prev parent reply other threads:[~2020-03-20 21:22 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-15 14:33 [RFC PATCH 0/3] arm64: hibernate: idmap the single page that holds the copy page routines James Morse
2020-01-15 14:33 ` [RFC PATCH 1/3] arm64: mm: Always update TCR_EL1 from __cpu_set_tcr_t0sz() James Morse
2020-01-15 14:33 ` [RFC PATCH 2/3] arm64: hibernate: Split create_safe_exec_page() and its mapping code James Morse
2020-01-15 14:33 ` [RFC PATCH 3/3] arm64: hibernate: idmap the single page that holds the copy page routines James Morse
2020-03-20 21:22 ` Pavel Tatashin [this message]
2020-03-25 9:58 ` James Morse
2020-03-25 13:29 ` Pavel Tatashin
2020-03-25 13:41 ` Pavel Tatashin
2020-03-25 17:08 ` James Morse
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