All of lore.kernel.org
 help / color / mirror / Atom feed
From: Will Deacon <will.deacon@arm.com>
To: yuanzhichang@hisilicon.com, dann.frazier@canonical.com,
	gabriele.paoloni@huawei.com, arnd@arndb.de, bhelgaas@google.com,
	andy.shevchenko@gmail.com
Cc: jean-philippe.brucker@arm.com, linux-pci@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, suzuki.poulose@arm.com
Subject: [REGRESSION] Commit 5745392e0c2b ("PCI: Apply the new generic I/O management on PCI IO hosts") breaks PCI for legacy virtio devices with kvmtool on arm64
Date: Fri, 7 Sep 2018 18:41:40 +0100	[thread overview]
Message-ID: <20180907174140.GI12788@arm.com> (raw)

Hi all,

I'm seeing a regression in Linux guests since 4.17 under kvmtool, where
legacy virtio devices using the PCI transport fail to probe. Legacy virtio
PCI devices must be accessed via "I/O space" (e.g. BAR0, which is
IORESOURCE_IO) and kvmtool assigns this to the guest physical range
0x0 - 0x10000.

On arm64, when the virtio legacy PCI driver calls pci_iomap() for this BAR,
it expands to ioport_map():

  static inline void __iomem *ioport_map(unsigned long port, unsigned int nr)
  {
  	return PCI_IOBASE + (port & MMIO_UPPER_LIMIT);
  }

Since the indirect PIO changes, MMIO_UPPER_LIMIT is defined as:

  /*
   * We reserve 0x4000 bytes for Indirect IO as so far this library is only
   * used by the HiSilicon LPC Host. If needed, we can reserve a wider IO
   * area by redefining the macro below.
   */
  #define PIO_INDIRECT_SIZE 0x4000
  #define MMIO_UPPER_LIMIT (IO_SPACE_LIMIT - PIO_INDIRECT_SIZE)

which corrupts the BAR address. For example, kvmtool has the BAR pointing
at 0x6200 on my system, but pci_iomap() actually maps offset 0x2200.
Changing PIO_INDIRECT_SIZE to 0 gets things working again.

Since this stuff doesn't revert nicely, I'm not sure how to proceed. Any
thoughts? Generally, having a per-platform magic constant hardcoded in
the PCI mapping code makes me feel slightly ill...

Cheers,

Will

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

WARNING: multiple messages have this Message-ID (diff)
From: will.deacon@arm.com (Will Deacon)
To: linux-arm-kernel@lists.infradead.org
Subject: [REGRESSION] Commit 5745392e0c2b ("PCI: Apply the new generic I/O management on PCI IO hosts") breaks PCI for legacy virtio devices with kvmtool on arm64
Date: Fri, 7 Sep 2018 18:41:40 +0100	[thread overview]
Message-ID: <20180907174140.GI12788@arm.com> (raw)

Hi all,

I'm seeing a regression in Linux guests since 4.17 under kvmtool, where
legacy virtio devices using the PCI transport fail to probe. Legacy virtio
PCI devices must be accessed via "I/O space" (e.g. BAR0, which is
IORESOURCE_IO) and kvmtool assigns this to the guest physical range
0x0 - 0x10000.

On arm64, when the virtio legacy PCI driver calls pci_iomap() for this BAR,
it expands to ioport_map():

  static inline void __iomem *ioport_map(unsigned long port, unsigned int nr)
  {
  	return PCI_IOBASE + (port & MMIO_UPPER_LIMIT);
  }

Since the indirect PIO changes, MMIO_UPPER_LIMIT is defined as:

  /*
   * We reserve 0x4000 bytes for Indirect IO as so far this library is only
   * used by the HiSilicon LPC Host. If needed, we can reserve a wider IO
   * area by redefining the macro below.
   */
  #define PIO_INDIRECT_SIZE 0x4000
  #define MMIO_UPPER_LIMIT (IO_SPACE_LIMIT - PIO_INDIRECT_SIZE)

which corrupts the BAR address. For example, kvmtool has the BAR pointing
at 0x6200 on my system, but pci_iomap() actually maps offset 0x2200.
Changing PIO_INDIRECT_SIZE to 0 gets things working again.

Since this stuff doesn't revert nicely, I'm not sure how to proceed. Any
thoughts? Generally, having a per-platform magic constant hardcoded in
the PCI mapping code makes me feel slightly ill...

Cheers,

Will

WARNING: multiple messages have this Message-ID (diff)
From: Will Deacon <will.deacon@arm.com>
To: yuanzhichang@hisilicon.com, dann.frazier@canonical.com,
	gabriele.paoloni@huawei.com, arnd@arndb.de, bhelgaas@google.com,
	andy.shevchenko@gmail.com
Cc: linux-arm-kernel@lists.infradead.org, linux-pci@vger.kernel.org,
	linux-kernel@vger.kernel.org, suzuki.poulose@arm.com,
	jean-philippe.brucker@arm.com
Subject: [REGRESSION] Commit 5745392e0c2b ("PCI: Apply the new generic I/O management on PCI IO hosts") breaks PCI for legacy virtio devices with kvmtool on arm64
Date: Fri, 7 Sep 2018 18:41:40 +0100	[thread overview]
Message-ID: <20180907174140.GI12788@arm.com> (raw)

Hi all,

I'm seeing a regression in Linux guests since 4.17 under kvmtool, where
legacy virtio devices using the PCI transport fail to probe. Legacy virtio
PCI devices must be accessed via "I/O space" (e.g. BAR0, which is
IORESOURCE_IO) and kvmtool assigns this to the guest physical range
0x0 - 0x10000.

On arm64, when the virtio legacy PCI driver calls pci_iomap() for this BAR,
it expands to ioport_map():

  static inline void __iomem *ioport_map(unsigned long port, unsigned int nr)
  {
  	return PCI_IOBASE + (port & MMIO_UPPER_LIMIT);
  }

Since the indirect PIO changes, MMIO_UPPER_LIMIT is defined as:

  /*
   * We reserve 0x4000 bytes for Indirect IO as so far this library is only
   * used by the HiSilicon LPC Host. If needed, we can reserve a wider IO
   * area by redefining the macro below.
   */
  #define PIO_INDIRECT_SIZE 0x4000
  #define MMIO_UPPER_LIMIT (IO_SPACE_LIMIT - PIO_INDIRECT_SIZE)

which corrupts the BAR address. For example, kvmtool has the BAR pointing
at 0x6200 on my system, but pci_iomap() actually maps offset 0x2200.
Changing PIO_INDIRECT_SIZE to 0 gets things working again.

Since this stuff doesn't revert nicely, I'm not sure how to proceed. Any
thoughts? Generally, having a per-platform magic constant hardcoded in
the PCI mapping code makes me feel slightly ill...

Cheers,

Will

             reply	other threads:[~2018-09-07 17:41 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-09-07 17:41 Will Deacon [this message]
2018-09-07 17:41 ` [REGRESSION] Commit 5745392e0c2b ("PCI: Apply the new generic I/O management on PCI IO hosts") breaks PCI for legacy virtio devices with kvmtool on arm64 Will Deacon
2018-09-07 17:41 ` Will Deacon
2018-09-12 11:50 ` Andrew Murray
2018-09-12 11:50   ` Andrew Murray

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20180907174140.GI12788@arm.com \
    --to=will.deacon@arm.com \
    --cc=andy.shevchenko@gmail.com \
    --cc=arnd@arndb.de \
    --cc=bhelgaas@google.com \
    --cc=dann.frazier@canonical.com \
    --cc=gabriele.paoloni@huawei.com \
    --cc=jean-philippe.brucker@arm.com \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-pci@vger.kernel.org \
    --cc=suzuki.poulose@arm.com \
    --cc=yuanzhichang@hisilicon.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.