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Re: [Qemu-devel] [PATCH v2] xen-platform: separate unplugging of NVMe di
From: |
Stefano Stabellini |
Subject: |
Re: [Qemu-devel] [PATCH v2] xen-platform: separate unplugging of NVMe disks |
Date: |
Thu, 23 Mar 2017 17:51:26 -0700 (PDT) |
User-agent: |
Alpine 2.10 (DEB 1266 2009-07-14) |
On Thu, 23 Mar 2017, Paul Durrant wrote:
> Commit 090fa1c8 "add support for unplugging NVMe disks..." extended the
> existing disk unplug flag to cover NVMe disks as well as IDE and SCSI.
>
> The recent thread on the xen-devel mailing list [1] has highlighted that
> this is not desirable behaviour: PV frontends should be able to distinguish
> NVMe disks from other types of disk and should have separate control over
> whether they are unplugged.
>
> This patch defines a new bit in the unplug mask for this purpose and also
> tidies up the definitions of, and improves the comments regarding, the
> previously exiting bits in the protocol.
>
> [1] https://lists.xen.org/archives/html/xen-devel/2017-03/msg02924.html
>
> Signed-off-by: Paul Durrant <address@hidden>
> --
> Cc: Stefano Stabellini <address@hidden>
> Cc: Anthony Perard <address@hidden>
>
> NOTE: A companion patch will be submitted to xen-devel to align the
> unplug protocol documentation once this patch is acked.
The companion patch needs to be acked before this patch gets applied. In
fact, I would prefer if the changeset of the Xen commit was added to
this patch description.
If you add that, then you can repost this with
Reviewed-by: Stefano Stabellini <address@hidden>
> v2:
> - Fix the commit comment
> ---
> hw/i386/xen/xen_platform.c | 47
> ++++++++++++++++++++++++++++++++++------------
> 1 file changed, 35 insertions(+), 12 deletions(-)
>
> diff --git a/hw/i386/xen/xen_platform.c b/hw/i386/xen/xen_platform.c
> index 6010f35..983d532 100644
> --- a/hw/i386/xen/xen_platform.c
> +++ b/hw/i386/xen/xen_platform.c
> @@ -87,10 +87,30 @@ static void log_writeb(PCIXenPlatformState *s, char val)
> }
> }
>
> -/* Xen Platform, Fixed IOPort */
> -#define UNPLUG_ALL_DISKS 1
> -#define UNPLUG_ALL_NICS 2
> -#define UNPLUG_AUX_IDE_DISKS 4
> +/*
> + * Unplug device flags.
> + *
> + * The logic got a little confused at some point in the past but this is
> + * what they do now.
> + *
> + * bit 0: Unplug all IDE and SCSI disks.
> + * bit 1: Unplug all NICs.
> + * bit 2: Unplug IDE disks except primary master. This is overridden if
> + * bit 0 is also present in the mask.
> + * bit 3: Unplug all NVMe disks.
> + *
> + */
> +#define _UNPLUG_IDE_SCSI_DISKS 0
> +#define UNPLUG_IDE_SCSI_DISKS (1u << _UNPLUG_IDE_SCSI_DISKS)
> +
> +#define _UNPLUG_ALL_NICS 1
> +#define UNPLUG_ALL_NICS (1u << _UNPLUG_ALL_NICS)
> +
> +#define _UNPLUG_AUX_IDE_DISKS 2
> +#define UNPLUG_AUX_IDE_DISKS (1u << _UNPLUG_AUX_IDE_DISKS)
> +
> +#define _UNPLUG_NVME_DISKS 3
> +#define UNPLUG_NVME_DISKS (1u << _UNPLUG_NVME_DISKS)
>
> static void unplug_nic(PCIBus *b, PCIDevice *d, void *o)
> {
> @@ -111,7 +131,7 @@ static void unplug_disks(PCIBus *b, PCIDevice *d, void
> *opaque)
> {
> uint32_t flags = *(uint32_t *)opaque;
> bool aux = (flags & UNPLUG_AUX_IDE_DISKS) &&
> - !(flags & UNPLUG_ALL_DISKS);
> + !(flags & UNPLUG_IDE_SCSI_DISKS);
>
> /* We have to ignore passthrough devices */
> if (!strcmp(d->name, "xen-pci-passthrough")) {
> @@ -124,12 +144,16 @@ static void unplug_disks(PCIBus *b, PCIDevice *d, void
> *opaque)
> break;
>
> case PCI_CLASS_STORAGE_SCSI:
> - case PCI_CLASS_STORAGE_EXPRESS:
> if (!aux) {
> object_unparent(OBJECT(d));
> }
> break;
>
> + case PCI_CLASS_STORAGE_EXPRESS:
> + if (flags & UNPLUG_NVME_DISKS) {
> + object_unparent(OBJECT(d));
> + }
> +
> default:
> break;
> }
> @@ -147,10 +171,9 @@ static void platform_fixed_ioport_writew(void *opaque,
> uint32_t addr, uint32_t v
> switch (addr) {
> case 0: {
> PCIDevice *pci_dev = PCI_DEVICE(s);
> - /* Unplug devices. Value is a bitmask of which devices to
> - unplug, with bit 0 the disk devices, bit 1 the network
> - devices, and bit 2 the non-primary-master IDE devices. */
> - if (val & (UNPLUG_ALL_DISKS | UNPLUG_AUX_IDE_DISKS)) {
> + /* Unplug devices. See comment above flag definitions */
> + if (val & (UNPLUG_IDE_SCSI_DISKS | UNPLUG_AUX_IDE_DISKS |
> + UNPLUG_NVME_DISKS)) {
> DPRINTF("unplug disks\n");
> pci_unplug_disks(pci_dev->bus, val);
> }
> @@ -338,14 +361,14 @@ static void xen_platform_ioport_writeb(void *opaque,
> hwaddr addr,
> * If VMDP was to control both disk and LAN it would use 4.
> * If it controlled just disk or just LAN, it would use 8 below.
> */
> - pci_unplug_disks(pci_dev->bus, UNPLUG_ALL_DISKS);
> + pci_unplug_disks(pci_dev->bus, UNPLUG_IDE_SCSI_DISKS);
> pci_unplug_nics(pci_dev->bus);
> }
> break;
> case 8:
> switch (val) {
> case 1:
> - pci_unplug_disks(pci_dev->bus, UNPLUG_ALL_DISKS);
> + pci_unplug_disks(pci_dev->bus, UNPLUG_IDE_SCSI_DISKS);
> break;
> case 2:
> pci_unplug_nics(pci_dev->bus);
> --
> 2.1.4
>