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From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Marek Vasut <marek.vasut@gmail.com>
Cc: Wolfram Sang <wsa@the-dreams.de>,
	linux-pci <linux-pci@vger.kernel.org>,
	Marek Vasut <marek.vasut+renesas@gmail.com>,
	Phil Edworthy <phil.edworthy@renesas.com>,
	Simon Horman <horms+renesas@verge.net.au>,
	Linux-Renesas <linux-renesas-soc@vger.kernel.org>
Subject: Re: [PATCH 2/3] PCI: rcar: Allow 64bit MSI addresses
Date: Mon, 18 Mar 2019 10:30:10 +0100	[thread overview]
Message-ID: <CAMuHMdWOL33eTMOWaHmxXpZoLmvMOtrcZN6Mi0REMbJvKwp+XQ@mail.gmail.com> (raw)
In-Reply-To: <CAMuHMdVXEqqRjkXR-9WPVVpNXu_C3Xg6yeZ0Nrhr1KbmHPuouw@mail.gmail.com>

Hi Marek,

On Mon, Mar 18, 2019 at 9:39 AM Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> On Mon, Mar 18, 2019 at 12:39 AM Marek Vasut <marek.vasut@gmail.com> wrote:
> > On 3/17/19 10:12 AM, Wolfram Sang wrote:
> > > On Sun, Mar 17, 2019 at 01:06:07AM +0100, marek.vasut@gmail.com wrote:
> > >> From: Marek Vasut <marek.vasut+renesas@gmail.com>
> > >>
> > >> The MSI address can be 64bit. Switch the data type used to hold the
> > >> result of virt_to_phys() to phys_addr_t to reflect it's properties
> > >> correctly and program the top 32bits of PA into PCIEMSIAUR.
> > >>
> > >> Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
> > >
> > > Looks sane. Not being a PCI expert, I wonder: Were we just lucky to not
> > > hit a 64-bit MSI address before?
> >
> > I wonder about that, virt_to_phys(__get_free_pages(GFP_KERNEL, 0)) would
> > happily return 64bit address, but with the cards I tested (a few intel
> > NICs [igb, e1000e], PCIe NVME SSDs and xHCI HCD), I am getting the MSIs
> > either way.
>
> No doubt you would be receiving the MSIs, if you have RAM at the truncated
> address, but wouldn't that cause memory corruption?
>
> Fixes: 290c1fb358605402 ("PCI: rcar: Add MSI support for PCIe")
>
> When MSI support was added, only R-Car H1 and Gen2 were supported.
> H1 doesn't have LPAE. Gen2 has, but it might have been disabled.

Correction: as this is always mapped kernel memory, LPAE doesn't matter.
So the bug matters for arm64 only.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

  reply	other threads:[~2019-03-18  9:30 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-17  0:06 [PATCH 1/3] PCI: rcar: Replace unsigned long with u32 for register values marek.vasut
2019-03-17  0:06 ` [PATCH 2/3] PCI: rcar: Allow 64bit MSI addresses marek.vasut
2019-03-17  8:03   ` Sergei Shtylyov
2019-03-17 22:59     ` Marek Vasut
2019-03-17  9:12   ` Wolfram Sang
2019-03-17 23:37     ` Marek Vasut
2019-03-18  8:39       ` Geert Uytterhoeven
2019-03-18  9:30         ` Geert Uytterhoeven [this message]
2019-03-19  1:16           ` Marek Vasut
2019-03-18  8:35   ` Geert Uytterhoeven
2019-03-22  2:30     ` Marek Vasut
2019-03-17  0:06 ` [PATCH 3/3] PCI: rcar: Clean up debug messages marek.vasut
2019-03-17  9:15   ` Wolfram Sang
2019-03-18  8:20   ` Geert Uytterhoeven
2019-03-17  9:09 ` [PATCH 1/3] PCI: rcar: Replace unsigned long with u32 for register values Wolfram Sang
2019-03-17 22:58   ` Marek Vasut
2019-03-18  7:33     ` Wolfram Sang
2019-03-18  8:47 ` Geert Uytterhoeven
2019-03-21  3:25   ` Marek Vasut
2019-03-21  7:31     ` Geert Uytterhoeven

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