Re: [Qemu-devel] [PATCH v2] e1000: add interrupt mitigation support

["Andreas Färber" <afaerber@suse.de>]

Hi,

Am 26.07.2013 12:14, schrieb Vincenzo Maffione:
>   I tried to support cross-version migration using version_id and
> VMState subsections.

The point of using a subsection is to avoid incrementing version_id AFAIU.

> I also disable MIT if the machine is "pc-i440fx-1.5": Is that the
> correct way to do it?

The usual way is to add a textual entry to compat_props, setting the
mitigation property on initialization. It is then not necessary to do
special post-load handling.

Please use git-send-email to send the patch inline, so that it can be
applied by tools. I.e., there should be no Date: or Subject: headers in
the body, and comments/questions can go under --- or in a cover letter.
http://wiki.qemu.org/Contribute/SubmitAPatch

Regards,
Andreas

> From 4e692113753db8dea6cbcc7a729cfa81469a76ca Mon Sep 17 00:00:00 2001
> From: Vincenzo Maffione <v.maffione@gmail.com>
> Date: Fri, 26 Jul 2013 11:58:33 +0200
> Subject: [PATCH] e1000: add interrupt mitigation support
> 
> This patch partially implements the e1000 interrupt mitigation mechanisms.
> Using a single QEMUTimer, it emulates the ITR register (which is the newer
> mitigation register, recommended by Intel) and approximately emulates
> RADV and TADV registers. TIDV and RDTR register functionalities are not
> emulated (RDTR is only used to validate RADV, according to the e1000 specs).
> 
> RADV, TADV, TIDV and RDTR registers make up the older e1000 mitigation
> mechanism and would need a timer each to be completely emulated. However,
> a single timer has been used in order to reach a good compromise between
> emulation accuracy and simplicity/efficiency.
> 
> The implemented mechanism can be enabled/disabled specifying the command
> line e1000-specific boolean parameter "mit", e.g.
> 
>     qemu-system-x86_64 -device e1000,mit=on,... ...
> 
> For more information, see the Software developer's manual at
> http://download.intel.com/design/network/manuals/8254x_GBe_SDM.pdf.
> 
> Signed-off-by: Vincenzo Maffione <v.maffione@gmail.com>
> ---
>  hw/net/e1000.c | 139 +++++++++++++++++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 135 insertions(+), 4 deletions(-)
> 
> diff --git a/hw/net/e1000.c b/hw/net/e1000.c
> index b952d8d..003b7ce 100644
> --- a/hw/net/e1000.c
> +++ b/hw/net/e1000.c
> @@ -135,9 +135,16 @@ typedef struct E1000State_st {
> 
>      QEMUTimer *autoneg_timer;
> 
> +    QEMUTimer *mit_timer;      /* Mitigation timer. */
> +    bool mit_timer_on;         /* Mitigation timer is running. */
> +    bool mit_irq_level;        /* Tracks interrupt pin level. */
> +    uint32_t mit_ide;          /* Tracks E1000_TXD_CMD_IDE bit. */
> +
>  /* Compatibility flags for migration to/from qemu 1.3.0 and older */
>  #define E1000_FLAG_AUTONEG_BIT 0
> +#define E1000_FLAG_MIT_BIT 1
>  #define E1000_FLAG_AUTONEG (1 << E1000_FLAG_AUTONEG_BIT)
> +#define E1000_FLAG_MIT (1 << E1000_FLAG_MIT_BIT)
>      uint32_t compat_flags;
>  } E1000State;
> 
> @@ -158,7 +165,8 @@ enum {
>      defreg(TORH),    defreg(TORL),    defreg(TOTH),    defreg(TOTL),
>      defreg(TPR),    defreg(TPT),    defreg(TXDCTL),    defreg(WUFC),
>      defreg(RA),        defreg(MTA),    defreg(CRCERRS),defreg(VFTA),
> -    defreg(VET),
> +    defreg(VET),        defreg(RDTR),   defreg(RADV),   defreg(TADV),
> +    defreg(ITR),
>  };
> 
>  static void
> @@ -245,10 +253,21 @@ static const uint32_t mac_reg_init[] = {
>                  E1000_MANC_RMCP_EN,
>  };
> 
> +/* Helper function, *curr == 0 means the value is not set */
> +static inline void
> +mit_update_delay(uint32_t *curr, uint32_t value)
> +{
> +    if (value && (*curr == 0 || value < *curr)) {
> +        *curr = value;
> +    }
> +}
> +
>  static void
>  set_interrupt_cause(E1000State *s, int index, uint32_t val)
>  {
>      PCIDevice *d = PCI_DEVICE(s);
> +    uint32_t pending_ints;
> +    uint32_t mit_delay;
> 
>      if (val && (E1000_DEVID >= E1000_DEV_ID_82547EI_MOBILE)) {
>          /* Only for 8257x */
> @@ -266,7 +285,57 @@ set_interrupt_cause(E1000State *s, int index, uint32_t val)
>       */
>      s->mac_reg[ICS] = val;
> 
> -    qemu_set_irq(d->irq[0], (s->mac_reg[IMS] & s->mac_reg[ICR]) != 0);
> +    pending_ints = (s->mac_reg[IMS] & s->mac_reg[ICR]);
> +    if (!s->mit_irq_level && pending_ints) {
> +        /*
> +         * Here we detect a potential raising edge. We postpone raising the
> +         * interrupt line if we are inside the mitigation delay window
> +         * (s->mit_timer_on == 1).
> +         * We provide a partial implementation of interrupt mitigation,
> +         * emulating only RADV, TADV and ITR (lower 16 bits, 1024ns units for
> +         * RADV and TADV, 256ns units for ITR). RDTR is only used to enable
> +         * RADV; relative timers based on TIDV and RDTR are not implemented.
> +         */
> +        if (s->mit_timer_on) {
> +            return;
> +        }
> +        if (s->compat_flags & E1000_FLAG_MIT) {
> +            /* Compute the next mitigation delay according to pending
> +             * interrupts and the current values of RADV (provided
> +             * RDTR!=0), TADV and ITR.
> +             * Then rearm the timer.
> +             */
> +            mit_delay = 0;
> +            if (s->mit_ide &&
> +                    (pending_ints & (E1000_ICR_TXQE | E1000_ICR_TXDW))) {
> +                mit_update_delay(&mit_delay, s->mac_reg[TADV] * 4);
> +            }
> +            if (s->mac_reg[RDTR] && (pending_ints & E1000_ICS_RXT0)) {
> +                mit_update_delay(&mit_delay, s->mac_reg[RADV] * 4);
> +            }
> +            mit_update_delay(&mit_delay, s->mac_reg[ITR]);
> +
> +            if (mit_delay) {
> +                s->mit_timer_on = 1;
> +                qemu_mod_timer(s->mit_timer,
> +                        qemu_get_clock_ns(vm_clock) + mit_delay * 256);
> +            }
> +            s->mit_ide = 0;
> +        }
> +    }
> +
> +    s->mit_irq_level = (pending_ints != 0);
> +    qemu_set_irq(d->irq[0], s->mit_irq_level);
> +}
> +
> +static void
> +e1000_mit_timer(void *opaque)
> +{
> +    E1000State *s = opaque;
> +
> +    s->mit_timer_on = 0;
> +    /* Call set_interrupt_cause to update the irq level (if necessary). */
> +    set_interrupt_cause(s, 0, s->mac_reg[ICR]);
>  }
> 
>  static void
> @@ -307,6 +376,10 @@ static void e1000_reset(void *opaque)
>      int i;
> 
>      qemu_del_timer(d->autoneg_timer);
> +    qemu_del_timer(d->mit_timer);
> +    d->mit_timer_on = 0;
> +    d->mit_irq_level = 0;
> +    d->mit_ide = 0;
>      memset(d->phy_reg, 0, sizeof d->phy_reg);
>      memmove(d->phy_reg, phy_reg_init, sizeof phy_reg_init);
>      memset(d->mac_reg, 0, sizeof d->mac_reg);
> @@ -572,6 +645,7 @@ process_tx_desc(E1000State *s, struct e1000_tx_desc *dp)
>      struct e1000_context_desc *xp = (struct e1000_context_desc *)dp;
>      struct e1000_tx *tp = &s->tx;
> 
> +    s->mit_ide |= (txd_lower & E1000_TXD_CMD_IDE);
>      if (dtype == E1000_TXD_CMD_DEXT) {    // context descriptor
>          op = le32_to_cpu(xp->cmd_and_length);
>          tp->ipcss = xp->lower_setup.ip_fields.ipcss;
> @@ -1047,7 +1121,8 @@ static uint32_t (*macreg_readops[])(E1000State *, int) = {
>      getreg(TORL),    getreg(TOTL),    getreg(IMS),    getreg(TCTL),
>      getreg(RDH),    getreg(RDT),    getreg(VET),    getreg(ICS),
>      getreg(TDBAL),    getreg(TDBAH),    getreg(RDBAH),    getreg(RDBAL),
> -    getreg(TDLEN),    getreg(RDLEN),
> +    getreg(TDLEN),      getreg(RDLEN),  getreg(RDTR),   getreg(RADV),
> +    getreg(TADV),       getreg(ITR),
> 
>      [TOTH] = mac_read_clr8,    [TORH] = mac_read_clr8,    [GPRC] =
> mac_read_clr4,
>      [GPTC] = mac_read_clr4,    [TPR] = mac_read_clr4,    [TPT] = mac_read_clr4,
> @@ -1069,6 +1144,8 @@ static void (*macreg_writeops[])(E1000State *,
> int, uint32_t) = {
>      [TDH] = set_16bit,    [RDH] = set_16bit,    [RDT] = set_rdt,
>      [IMC] = set_imc,    [IMS] = set_ims,    [ICR] = set_icr,
>      [EECD] = set_eecd,    [RCTL] = set_rx_control, [CTRL] = set_ctrl,
> +    [RDTR] = set_16bit, [RADV] = set_16bit,     [TADV] = set_16bit,
> +    [ITR] = set_16bit,
>      [RA ... RA+31] = &mac_writereg,
>      [MTA ... MTA+127] = &mac_writereg,
>      [VFTA ... VFTA+127] = &mac_writereg,
> @@ -1150,6 +1227,11 @@ static void e1000_pre_save(void *opaque)
>      E1000State *s = opaque;
>      NetClientState *nc = qemu_get_queue(s->nic);
> 
> +    /* If the mitigation timer is active, emulate a timeout now. */
> +    if (s->mit_timer_on) {
> +        e1000_mit_timer(s);
> +    }
> +
>      if (!(s->compat_flags & E1000_FLAG_AUTONEG)) {
>          return;
>      }
> @@ -1171,6 +1253,12 @@ static int e1000_post_load(void *opaque, int version_id)
>      E1000State *s = opaque;
>      NetClientState *nc = qemu_get_queue(s->nic);
> 
> +    if (version_id < 3 || !(s->compat_flags & E1000_FLAG_MIT)) {
> +        s->mac_reg[ITR] = s->mac_reg[RDTR] = s->mac_reg[RADV] =
> +            s->mac_reg[TADV] = s->mit_ide = 0;
> +        s->mit_timer_on = s->mit_irq_level = false;
> +    }
> +
>      /* nc.link_down can't be migrated, so infer link_down according
>       * to link status bit in mac_reg[STATUS].
>       * Alternatively, restart link negotiation if it was in progress. */
> @@ -1190,9 +1278,33 @@ static int e1000_post_load(void *opaque, int version_id)
>      return 0;
>  }
> 
> +static bool e1000_mit_state_needed(void *opaque)
> +{
> +    E1000State *s = opaque;
> +
> +    return s->compat_flags & E1000_FLAG_MIT;
> +}
> +
> +static const VMStateDescription vmstate_e1000_mit_state = {
> +    .name = "e1000/mit_state",
> +    .version_id = 1,
> +    .minimum_version_id = 1,
> +    .minimum_version_id_old = 1,
> +    .fields    = (VMStateField[]) {
> +        VMSTATE_UINT32(mac_reg[RDTR], E1000State),
> +        VMSTATE_UINT32(mac_reg[RADV], E1000State),
> +        VMSTATE_UINT32(mac_reg[TADV], E1000State),
> +        VMSTATE_UINT32(mac_reg[ITR], E1000State),
> +        VMSTATE_BOOL(mit_timer_on, E1000State),
> +        VMSTATE_BOOL(mit_irq_level, E1000State),
> +        VMSTATE_UINT32(mit_ide, E1000State),
> +        VMSTATE_END_OF_LIST()
> +    }
> +};
> +
>  static const VMStateDescription vmstate_e1000 = {
>      .name = "e1000",
> -    .version_id = 2,
> +    .version_id = 3,
>      .minimum_version_id = 1,
>      .minimum_version_id_old = 1,
>      .pre_save = e1000_pre_save,
> @@ -1267,6 +1379,14 @@ static const VMStateDescription vmstate_e1000 = {
>          VMSTATE_UINT32_SUB_ARRAY(mac_reg, E1000State, MTA, 128),
>          VMSTATE_UINT32_SUB_ARRAY(mac_reg, E1000State, VFTA, 128),
>          VMSTATE_END_OF_LIST()
> +    },
> +    .subsections = (VMStateSubsection[]) {
> +        {
> +            .vmsd = &vmstate_e1000_mit_state,
> +            .needed = e1000_mit_state_needed,
> +        }, {
> +            /* empty */
> +        }
>      }
>  };
> 
> @@ -1316,6 +1436,8 @@ pci_e1000_uninit(PCIDevice *dev)
> 
>      qemu_del_timer(d->autoneg_timer);
>      qemu_free_timer(d->autoneg_timer);
> +    qemu_del_timer(d->mit_timer);
> +    qemu_free_timer(d->mit_timer);
>      memory_region_destroy(&d->mmio);
>      memory_region_destroy(&d->io);
>      qemu_del_nic(d->nic);
> @@ -1338,6 +1460,7 @@ static int pci_e1000_init(PCIDevice *pci_dev)
>      uint16_t checksum = 0;
>      int i;
>      uint8_t *macaddr;
> +    const char *machine_type;
> 
>      pci_conf = pci_dev->config;
> 
> @@ -1371,6 +1494,12 @@ static int pci_e1000_init(PCIDevice *pci_dev)
>      add_boot_device_path(d->conf.bootindex, dev, "/ethernet-phy@0");
> 
>      d->autoneg_timer = qemu_new_timer_ms(vm_clock, e1000_autoneg_timer, d);
> +    d->mit_timer = qemu_new_timer_ns(vm_clock, e1000_mit_timer, d);
> +
> +    machine_type = qemu_opt_get(qemu_get_machine_opts(), "type");
> +    if (machine_type && strcmp(machine_type, "pc-i440fx-1.5") == 0) {
> +        d->compat_flags &= ~E1000_FLAG_MIT;
> +    }
> 
>      return 0;
>  }
> @@ -1385,6 +1514,8 @@ static Property e1000_properties[] = {
>      DEFINE_NIC_PROPERTIES(E1000State, conf),
>      DEFINE_PROP_BIT("autonegotiation", E1000State,
>                      compat_flags, E1000_FLAG_AUTONEG_BIT, true),
> +    DEFINE_PROP_BIT("mitigation", E1000State,
> +                    compat_flags, E1000_FLAG_MIT_BIT, true),
>      DEFINE_PROP_END_OF_LIST(),
>  };
> 


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