diff mbox series

[v5,08/12] net: cadence_gem: Add support for jumbo frames

Message ID 1589295294-26466-9-git-send-email-sai.pavan.boddu@xilinx.com
State New
Headers show
Series Cadence GEM Fixes | expand

Commit Message

Sai Pavan Boddu May 12, 2020, 2:54 p.m. UTC 
Add a property "jumbo-max-len", which sets default value of jumbo frames
up to 16,383 bytes. Add Frame length checks for standard and jumbo
frames.

Signed-off-by: Sai Pavan Boddu <sai.pavan.boddu@xilinx.com>
---
 hw/net/cadence_gem.c         | 51 +++++++++++++++++++++++++++++++++++++++-----
 include/hw/net/cadence_gem.h |  4 +++-
 2 files changed, 49 insertions(+), 6 deletions(-)

Comments

Edgar E. Iglesias May 12, 2020, 3:19 p.m. UTC | #1 
On Tue, May 12, 2020 at 08:24:50PM +0530, Sai Pavan Boddu wrote:
> Add a property "jumbo-max-len", which sets default value of jumbo frames
> up to 16,383 bytes. Add Frame length checks for standard and jumbo
> frames.

Reviewed-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>



> 
> Signed-off-by: Sai Pavan Boddu <sai.pavan.boddu@xilinx.com>
> ---
>  hw/net/cadence_gem.c         | 51 +++++++++++++++++++++++++++++++++++++++-----
>  include/hw/net/cadence_gem.h |  4 +++-
>  2 files changed, 49 insertions(+), 6 deletions(-)
> 
> diff --git a/hw/net/cadence_gem.c b/hw/net/cadence_gem.c
> index f6ff27c..eb02946 100644
> --- a/hw/net/cadence_gem.c
> +++ b/hw/net/cadence_gem.c
> @@ -61,6 +61,7 @@
>  #define GEM_TXPAUSE       (0x0000003C / 4) /* TX Pause Time reg */
>  #define GEM_TXPARTIALSF   (0x00000040 / 4) /* TX Partial Store and Forward */
>  #define GEM_RXPARTIALSF   (0x00000044 / 4) /* RX Partial Store and Forward */
> +#define GEM_JUMBO_MAX_LEN (0x00000048 / 4) /* Max Jumbo Frame Size */
>  #define GEM_HASHLO        (0x00000080 / 4) /* Hash Low address reg */
>  #define GEM_HASHHI        (0x00000084 / 4) /* Hash High address reg */
>  #define GEM_SPADDR1LO     (0x00000088 / 4) /* Specific addr 1 low reg */
> @@ -212,10 +213,12 @@
>  #define GEM_NWCFG_LERR_DISC    0x00010000 /* Discard RX frames with len err */
>  #define GEM_NWCFG_BUFF_OFST_M  0x0000C000 /* Receive buffer offset mask */
>  #define GEM_NWCFG_BUFF_OFST_S  14         /* Receive buffer offset shift */
> +#define GEM_NWCFG_RCV_1538     0x00000100 /* Receive 1538 bytes frame */
>  #define GEM_NWCFG_UCAST_HASH   0x00000080 /* accept unicast if hash match */
>  #define GEM_NWCFG_MCAST_HASH   0x00000040 /* accept multicast if hash match */
>  #define GEM_NWCFG_BCAST_REJ    0x00000020 /* Reject broadcast packets */
>  #define GEM_NWCFG_PROMISC      0x00000010 /* Accept all packets */
> +#define GEM_NWCFG_JUMBO_FRAME  0x00000008 /* Jumbo Frames enable */
>  
>  #define GEM_DMACFG_ADDR_64B    (1U << 30)
>  #define GEM_DMACFG_TX_BD_EXT   (1U << 29)
> @@ -233,6 +236,7 @@
>  
>  /* GEM_ISR GEM_IER GEM_IDR GEM_IMR */
>  #define GEM_INT_TXCMPL        0x00000080 /* Transmit Complete */
> +#define GEM_INT_AMBA_ERR      0x00000040
>  #define GEM_INT_TXUSED         0x00000008
>  #define GEM_INT_RXUSED         0x00000004
>  #define GEM_INT_RXCMPL        0x00000002
> @@ -453,6 +457,24 @@ static inline void rx_desc_set_sar(uint32_t *desc, int sar_idx)
>  /* The broadcast MAC address: 0xFFFFFFFFFFFF */
>  static const uint8_t broadcast_addr[] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };
>  
> +static uint32_t gem_get_max_buf_len(CadenceGEMState *s, bool tx)
> +{
> +    uint32_t size;
> +    if (s->regs[GEM_NWCFG] & GEM_NWCFG_JUMBO_FRAME) {
> +        size = s->regs[GEM_JUMBO_MAX_LEN];
> +        if (size > s->jumbo_max_len) {
> +            size = s->jumbo_max_len;
> +            qemu_log_mask(LOG_GUEST_ERROR, "GEM_JUMBO_MAX_LEN reg cannot be"
> +                " greater than 0x%" PRIx32 "\n", s->jumbo_max_len);
> +        }
> +    } else if (tx) {
> +        size = 1518;
> +    } else {
> +        size = s->regs[GEM_NWCFG] & GEM_NWCFG_RCV_1538 ? 1538 : 1518;
> +    }
> +    return size;
> +}
> +
>  static void gem_set_isr(CadenceGEMState *s, int q, uint32_t flag)
>  {
>      if (q == 0) {
> @@ -1016,6 +1038,12 @@ static ssize_t gem_receive(NetClientState *nc, const uint8_t *buf, size_t size)
>      /* Find which queue we are targeting */
>      q = get_queue_from_screen(s, rxbuf_ptr, rxbufsize);
>  
> +    if (size > gem_get_max_buf_len(s, false)) {
> +        qemu_log_mask(LOG_GUEST_ERROR, "rx frame too long\n");
> +        gem_set_isr(s, q, GEM_INT_AMBA_ERR);
> +        return -1;
> +    }
> +
>      while (bytes_to_copy) {
>          hwaddr desc_addr;
>  
> @@ -1196,12 +1224,13 @@ static void gem_transmit(CadenceGEMState *s)
>                  break;
>              }
>  
> -            if (tx_desc_get_length(desc) > MAX_FRAME_SIZE -
> +            if (tx_desc_get_length(desc) > gem_get_max_buf_len(s, true) -
>                                                 (p - s->tx_packet)) {
> -                DB_PRINT("TX descriptor @ 0x%" HWADDR_PRIx \
> -                         " too large: size 0x%x space 0x%zx\n",
> +                qemu_log_mask(LOG_GUEST_ERROR, "TX descriptor @ 0x%" \
> +                         HWADDR_PRIx " too large: size 0x%x space 0x%zx\n",
>                           packet_desc_addr, tx_desc_get_length(desc),
> -                         MAX_FRAME_SIZE - (p - s->tx_packet));
> +                         gem_get_max_buf_len(s, true) - (p - s->tx_packet));
> +                gem_set_isr(s, q, GEM_INT_AMBA_ERR);
>                  break;
>              }
>  
> @@ -1343,9 +1372,10 @@ static void gem_reset(DeviceState *d)
>      s->regs[GEM_RXPARTIALSF] = 0x000003ff;
>      s->regs[GEM_MODID] = s->revision;
>      s->regs[GEM_DESCONF] = 0x02500111;
> -    s->regs[GEM_DESCONF2] = 0x2ab13fff;
> +    s->regs[GEM_DESCONF2] = 0x2ab10000 | s->jumbo_max_len;
>      s->regs[GEM_DESCONF5] = 0x002f2045;
>      s->regs[GEM_DESCONF6] = GEM_DESCONF6_64B_MASK;
> +    s->regs[GEM_JUMBO_MAX_LEN] = s->jumbo_max_len;
>  
>      if (s->num_priority_queues > 1) {
>          queues_mask = MAKE_64BIT_MASK(1, s->num_priority_queues - 1);
> @@ -1516,6 +1546,9 @@ static void gem_write(void *opaque, hwaddr offset, uint64_t val,
>          s->regs[GEM_IMR] &= ~val;
>          gem_update_int_status(s);
>          break;
> +    case GEM_JUMBO_MAX_LEN:
> +        s->regs[GEM_JUMBO_MAX_LEN] = val & MAX_JUMBO_FRAME_SIZE_MASK;
> +        break;
>      case GEM_INT_Q1_ENABLE ... GEM_INT_Q7_ENABLE:
>          s->regs[GEM_INT_Q1_MASK + offset - GEM_INT_Q1_ENABLE] &= ~val;
>          gem_update_int_status(s);
> @@ -1610,6 +1643,12 @@ static void gem_realize(DeviceState *dev, Error **errp)
>  
>      s->nic = qemu_new_nic(&net_gem_info, &s->conf,
>                            object_get_typename(OBJECT(dev)), dev->id, s);
> +
> +    if (s->jumbo_max_len > MAX_FRAME_SIZE) {
> +        error_setg(errp, "jumbo-max-len is greater than %d",
> +                  MAX_FRAME_SIZE);
> +        return;
> +    }
>  }
>  
>  static void gem_init(Object *obj)
> @@ -1659,6 +1698,8 @@ static Property gem_properties[] = {
>                        num_type1_screeners, 4),
>      DEFINE_PROP_UINT8("num-type2-screeners", CadenceGEMState,
>                        num_type2_screeners, 4),
> +    DEFINE_PROP_UINT16("jumbo-max-len", CadenceGEMState,
> +                       jumbo_max_len, 10240),
>      DEFINE_PROP_END_OF_LIST(),
>  };
>  
> diff --git a/include/hw/net/cadence_gem.h b/include/hw/net/cadence_gem.h
> index eddac70..54e646f 100644
> --- a/include/hw/net/cadence_gem.h
> +++ b/include/hw/net/cadence_gem.h
> @@ -40,7 +40,8 @@
>  #define MAX_TYPE1_SCREENERS             16
>  #define MAX_TYPE2_SCREENERS             16
>  
> -#define MAX_FRAME_SIZE 2048
> +#define MAX_JUMBO_FRAME_SIZE_MASK 0x3FFF
> +#define MAX_FRAME_SIZE MAX_JUMBO_FRAME_SIZE_MASK
>  
>  typedef struct CadenceGEMState {
>      /*< private >*/
> @@ -59,6 +60,7 @@ typedef struct CadenceGEMState {
>      uint8_t num_type1_screeners;
>      uint8_t num_type2_screeners;
>      uint32_t revision;
> +    uint16_t jumbo_max_len;
>  
>      /* GEM registers backing store */
>      uint32_t regs[CADENCE_GEM_MAXREG];
> -- 
> 2.7.4
>
Sai Pavan Boddu May 13, 2020, 5:15 a.m. UTC | #2 
Thanks for review edgar!

Regards,
Sai pavan

> -----Original Message-----
> From: Edgar E. Iglesias <edgar.iglesias@gmail.com>
> Sent: Tuesday, May 12, 2020 8:50 PM
> To: Sai Pavan Boddu <saipava@xilinx.com>
> Cc: Alistair Francis <Alistair.Francis@wdc.com>; Peter Maydell
> <peter.maydell@linaro.org>; Jason Wang <jasowang@redhat.com>; Markus
> Armbruster <armbru@redhat.com>; Philippe Mathieu-Daudé
> <philmd@redhat.com>; Tong Ho <tongh@xilinx.com>; Ramon Fried
> <rfried.dev@gmail.com>; qemu-arm@nongnu.org; qemu-
> devel@nongnu.org
> Subject: Re: [PATCH v5 08/12] net: cadence_gem: Add support for jumbo
> frames
> 
> On Tue, May 12, 2020 at 08:24:50PM +0530, Sai Pavan Boddu wrote:
> > Add a property "jumbo-max-len", which sets default value of jumbo
> > frames up to 16,383 bytes. Add Frame length checks for standard and
> > jumbo frames.
> 
> Reviewed-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
> 
> 
> 
> >
> > Signed-off-by: Sai Pavan Boddu <sai.pavan.boddu@xilinx.com>
> > ---
> >  hw/net/cadence_gem.c         | 51
> +++++++++++++++++++++++++++++++++++++++-----
> >  include/hw/net/cadence_gem.h |  4 +++-
> >  2 files changed, 49 insertions(+), 6 deletions(-)
> >
> > diff --git a/hw/net/cadence_gem.c b/hw/net/cadence_gem.c index
> > f6ff27c..eb02946 100644
> > --- a/hw/net/cadence_gem.c
> > +++ b/hw/net/cadence_gem.c
> > @@ -61,6 +61,7 @@
> >  #define GEM_TXPAUSE       (0x0000003C / 4) /* TX Pause Time reg */
> >  #define GEM_TXPARTIALSF   (0x00000040 / 4) /* TX Partial Store and
> Forward */
> >  #define GEM_RXPARTIALSF   (0x00000044 / 4) /* RX Partial Store and
> Forward */
> > +#define GEM_JUMBO_MAX_LEN (0x00000048 / 4) /* Max Jumbo Frame
> Size */
> >  #define GEM_HASHLO        (0x00000080 / 4) /* Hash Low address reg */
> >  #define GEM_HASHHI        (0x00000084 / 4) /* Hash High address reg */
> >  #define GEM_SPADDR1LO     (0x00000088 / 4) /* Specific addr 1 low reg */
> > @@ -212,10 +213,12 @@
> >  #define GEM_NWCFG_LERR_DISC    0x00010000 /* Discard RX frames with
> len err */
> >  #define GEM_NWCFG_BUFF_OFST_M  0x0000C000 /* Receive buffer
> offset mask */
> >  #define GEM_NWCFG_BUFF_OFST_S  14         /* Receive buffer offset shift
> */
> > +#define GEM_NWCFG_RCV_1538     0x00000100 /* Receive 1538 bytes
> frame */
> >  #define GEM_NWCFG_UCAST_HASH   0x00000080 /* accept unicast if hash
> match */
> >  #define GEM_NWCFG_MCAST_HASH   0x00000040 /* accept multicast if
> hash match */
> >  #define GEM_NWCFG_BCAST_REJ    0x00000020 /* Reject broadcast
> packets */
> >  #define GEM_NWCFG_PROMISC      0x00000010 /* Accept all packets */
> > +#define GEM_NWCFG_JUMBO_FRAME  0x00000008 /* Jumbo Frames
> enable */
> >
> >  #define GEM_DMACFG_ADDR_64B    (1U << 30)
> >  #define GEM_DMACFG_TX_BD_EXT   (1U << 29)
> > @@ -233,6 +236,7 @@
> >
> >  /* GEM_ISR GEM_IER GEM_IDR GEM_IMR */
> >  #define GEM_INT_TXCMPL        0x00000080 /* Transmit Complete */
> > +#define GEM_INT_AMBA_ERR      0x00000040
> >  #define GEM_INT_TXUSED         0x00000008
> >  #define GEM_INT_RXUSED         0x00000004
> >  #define GEM_INT_RXCMPL        0x00000002
> > @@ -453,6 +457,24 @@ static inline void rx_desc_set_sar(uint32_t
> > *desc, int sar_idx)
> >  /* The broadcast MAC address: 0xFFFFFFFFFFFF */  static const uint8_t
> > broadcast_addr[] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };
> >
> > +static uint32_t gem_get_max_buf_len(CadenceGEMState *s, bool tx) {
> > +    uint32_t size;
> > +    if (s->regs[GEM_NWCFG] & GEM_NWCFG_JUMBO_FRAME) {
> > +        size = s->regs[GEM_JUMBO_MAX_LEN];
> > +        if (size > s->jumbo_max_len) {
> > +            size = s->jumbo_max_len;
> > +            qemu_log_mask(LOG_GUEST_ERROR, "GEM_JUMBO_MAX_LEN
> reg cannot be"
> > +                " greater than 0x%" PRIx32 "\n", s->jumbo_max_len);
> > +        }
> > +    } else if (tx) {
> > +        size = 1518;
> > +    } else {
> > +        size = s->regs[GEM_NWCFG] & GEM_NWCFG_RCV_1538 ? 1538 :
> 1518;
> > +    }
> > +    return size;
> > +}
> > +
> >  static void gem_set_isr(CadenceGEMState *s, int q, uint32_t flag)  {
> >      if (q == 0) {
> > @@ -1016,6 +1038,12 @@ static ssize_t gem_receive(NetClientState *nc,
> const uint8_t *buf, size_t size)
> >      /* Find which queue we are targeting */
> >      q = get_queue_from_screen(s, rxbuf_ptr, rxbufsize);
> >
> > +    if (size > gem_get_max_buf_len(s, false)) {
> > +        qemu_log_mask(LOG_GUEST_ERROR, "rx frame too long\n");
> > +        gem_set_isr(s, q, GEM_INT_AMBA_ERR);
> > +        return -1;
> > +    }
> > +
> >      while (bytes_to_copy) {
> >          hwaddr desc_addr;
> >
> > @@ -1196,12 +1224,13 @@ static void gem_transmit(CadenceGEMState
> *s)
> >                  break;
> >              }
> >
> > -            if (tx_desc_get_length(desc) > MAX_FRAME_SIZE -
> > +            if (tx_desc_get_length(desc) > gem_get_max_buf_len(s,
> > + true) -
> >                                                 (p - s->tx_packet)) {
> > -                DB_PRINT("TX descriptor @ 0x%" HWADDR_PRIx \
> > -                         " too large: size 0x%x space 0x%zx\n",
> > +                qemu_log_mask(LOG_GUEST_ERROR, "TX descriptor @ 0x%" \
> > +                         HWADDR_PRIx " too large: size 0x%x space
> > + 0x%zx\n",
> >                           packet_desc_addr, tx_desc_get_length(desc),
> > -                         MAX_FRAME_SIZE - (p - s->tx_packet));
> > +                         gem_get_max_buf_len(s, true) - (p - s->tx_packet));
> > +                gem_set_isr(s, q, GEM_INT_AMBA_ERR);
> >                  break;
> >              }
> >
> > @@ -1343,9 +1372,10 @@ static void gem_reset(DeviceState *d)
> >      s->regs[GEM_RXPARTIALSF] = 0x000003ff;
> >      s->regs[GEM_MODID] = s->revision;
> >      s->regs[GEM_DESCONF] = 0x02500111;
> > -    s->regs[GEM_DESCONF2] = 0x2ab13fff;
> > +    s->regs[GEM_DESCONF2] = 0x2ab10000 | s->jumbo_max_len;
> >      s->regs[GEM_DESCONF5] = 0x002f2045;
> >      s->regs[GEM_DESCONF6] = GEM_DESCONF6_64B_MASK;
> > +    s->regs[GEM_JUMBO_MAX_LEN] = s->jumbo_max_len;
> >
> >      if (s->num_priority_queues > 1) {
> >          queues_mask = MAKE_64BIT_MASK(1, s->num_priority_queues - 1);
> > @@ -1516,6 +1546,9 @@ static void gem_write(void *opaque, hwaddr
> offset, uint64_t val,
> >          s->regs[GEM_IMR] &= ~val;
> >          gem_update_int_status(s);
> >          break;
> > +    case GEM_JUMBO_MAX_LEN:
> > +        s->regs[GEM_JUMBO_MAX_LEN] = val &
> MAX_JUMBO_FRAME_SIZE_MASK;
> > +        break;
> >      case GEM_INT_Q1_ENABLE ... GEM_INT_Q7_ENABLE:
> >          s->regs[GEM_INT_Q1_MASK + offset - GEM_INT_Q1_ENABLE] &=
> ~val;
> >          gem_update_int_status(s);
> > @@ -1610,6 +1643,12 @@ static void gem_realize(DeviceState *dev, Error
> > **errp)
> >
> >      s->nic = qemu_new_nic(&net_gem_info, &s->conf,
> >                            object_get_typename(OBJECT(dev)), dev->id,
> > s);
> > +
> > +    if (s->jumbo_max_len > MAX_FRAME_SIZE) {
> > +        error_setg(errp, "jumbo-max-len is greater than %d",
> > +                  MAX_FRAME_SIZE);
> > +        return;
> > +    }
> >  }
> >
> >  static void gem_init(Object *obj)
> > @@ -1659,6 +1698,8 @@ static Property gem_properties[] = {
> >                        num_type1_screeners, 4),
> >      DEFINE_PROP_UINT8("num-type2-screeners", CadenceGEMState,
> >                        num_type2_screeners, 4),
> > +    DEFINE_PROP_UINT16("jumbo-max-len", CadenceGEMState,
> > +                       jumbo_max_len, 10240),
> >      DEFINE_PROP_END_OF_LIST(),
> >  };
> >
> > diff --git a/include/hw/net/cadence_gem.h
> > b/include/hw/net/cadence_gem.h index eddac70..54e646f 100644
> > --- a/include/hw/net/cadence_gem.h
> > +++ b/include/hw/net/cadence_gem.h
> > @@ -40,7 +40,8 @@
> >  #define MAX_TYPE1_SCREENERS             16
> >  #define MAX_TYPE2_SCREENERS             16
> >
> > -#define MAX_FRAME_SIZE 2048
> > +#define MAX_JUMBO_FRAME_SIZE_MASK 0x3FFF #define
> MAX_FRAME_SIZE
> > +MAX_JUMBO_FRAME_SIZE_MASK
> >
> >  typedef struct CadenceGEMState {
> >      /*< private >*/
> > @@ -59,6 +60,7 @@ typedef struct CadenceGEMState {
> >      uint8_t num_type1_screeners;
> >      uint8_t num_type2_screeners;
> >      uint32_t revision;
> > +    uint16_t jumbo_max_len;
> >
> >      /* GEM registers backing store */
> >      uint32_t regs[CADENCE_GEM_MAXREG];
> > --
> > 2.7.4
> >
diff mbox series

Patch

diff --git a/hw/net/cadence_gem.c b/hw/net/cadence_gem.c
index f6ff27c..eb02946 100644
--- a/hw/net/cadence_gem.c
+++ b/hw/net/cadence_gem.c
@@ -61,6 +61,7 @@ 
 #define GEM_TXPAUSE       (0x0000003C / 4) /* TX Pause Time reg */
 #define GEM_TXPARTIALSF   (0x00000040 / 4) /* TX Partial Store and Forward */
 #define GEM_RXPARTIALSF   (0x00000044 / 4) /* RX Partial Store and Forward */
+#define GEM_JUMBO_MAX_LEN (0x00000048 / 4) /* Max Jumbo Frame Size */
 #define GEM_HASHLO        (0x00000080 / 4) /* Hash Low address reg */
 #define GEM_HASHHI        (0x00000084 / 4) /* Hash High address reg */
 #define GEM_SPADDR1LO     (0x00000088 / 4) /* Specific addr 1 low reg */
@@ -212,10 +213,12 @@ 
 #define GEM_NWCFG_LERR_DISC    0x00010000 /* Discard RX frames with len err */
 #define GEM_NWCFG_BUFF_OFST_M  0x0000C000 /* Receive buffer offset mask */
 #define GEM_NWCFG_BUFF_OFST_S  14         /* Receive buffer offset shift */
+#define GEM_NWCFG_RCV_1538     0x00000100 /* Receive 1538 bytes frame */
 #define GEM_NWCFG_UCAST_HASH   0x00000080 /* accept unicast if hash match */
 #define GEM_NWCFG_MCAST_HASH   0x00000040 /* accept multicast if hash match */
 #define GEM_NWCFG_BCAST_REJ    0x00000020 /* Reject broadcast packets */
 #define GEM_NWCFG_PROMISC      0x00000010 /* Accept all packets */
+#define GEM_NWCFG_JUMBO_FRAME  0x00000008 /* Jumbo Frames enable */
 
 #define GEM_DMACFG_ADDR_64B    (1U << 30)
 #define GEM_DMACFG_TX_BD_EXT   (1U << 29)
@@ -233,6 +236,7 @@ 
 
 /* GEM_ISR GEM_IER GEM_IDR GEM_IMR */
 #define GEM_INT_TXCMPL        0x00000080 /* Transmit Complete */
+#define GEM_INT_AMBA_ERR      0x00000040
 #define GEM_INT_TXUSED         0x00000008
 #define GEM_INT_RXUSED         0x00000004
 #define GEM_INT_RXCMPL        0x00000002
@@ -453,6 +457,24 @@  static inline void rx_desc_set_sar(uint32_t *desc, int sar_idx)
 /* The broadcast MAC address: 0xFFFFFFFFFFFF */
 static const uint8_t broadcast_addr[] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };
 
+static uint32_t gem_get_max_buf_len(CadenceGEMState *s, bool tx)
+{
+    uint32_t size;
+    if (s->regs[GEM_NWCFG] & GEM_NWCFG_JUMBO_FRAME) {
+        size = s->regs[GEM_JUMBO_MAX_LEN];
+        if (size > s->jumbo_max_len) {
+            size = s->jumbo_max_len;
+            qemu_log_mask(LOG_GUEST_ERROR, "GEM_JUMBO_MAX_LEN reg cannot be"
+                " greater than 0x%" PRIx32 "\n", s->jumbo_max_len);
+        }
+    } else if (tx) {
+        size = 1518;
+    } else {
+        size = s->regs[GEM_NWCFG] & GEM_NWCFG_RCV_1538 ? 1538 : 1518;
+    }
+    return size;
+}
+
 static void gem_set_isr(CadenceGEMState *s, int q, uint32_t flag)
 {
     if (q == 0) {
@@ -1016,6 +1038,12 @@  static ssize_t gem_receive(NetClientState *nc, const uint8_t *buf, size_t size)
     /* Find which queue we are targeting */
     q = get_queue_from_screen(s, rxbuf_ptr, rxbufsize);
 
+    if (size > gem_get_max_buf_len(s, false)) {
+        qemu_log_mask(LOG_GUEST_ERROR, "rx frame too long\n");
+        gem_set_isr(s, q, GEM_INT_AMBA_ERR);
+        return -1;
+    }
+
     while (bytes_to_copy) {
         hwaddr desc_addr;
 
@@ -1196,12 +1224,13 @@  static void gem_transmit(CadenceGEMState *s)
                 break;
             }
 
-            if (tx_desc_get_length(desc) > MAX_FRAME_SIZE -
+            if (tx_desc_get_length(desc) > gem_get_max_buf_len(s, true) -
                                                (p - s->tx_packet)) {
-                DB_PRINT("TX descriptor @ 0x%" HWADDR_PRIx \
-                         " too large: size 0x%x space 0x%zx\n",
+                qemu_log_mask(LOG_GUEST_ERROR, "TX descriptor @ 0x%" \
+                         HWADDR_PRIx " too large: size 0x%x space 0x%zx\n",
                          packet_desc_addr, tx_desc_get_length(desc),
-                         MAX_FRAME_SIZE - (p - s->tx_packet));
+                         gem_get_max_buf_len(s, true) - (p - s->tx_packet));
+                gem_set_isr(s, q, GEM_INT_AMBA_ERR);
                 break;
             }
 
@@ -1343,9 +1372,10 @@  static void gem_reset(DeviceState *d)
     s->regs[GEM_RXPARTIALSF] = 0x000003ff;
     s->regs[GEM_MODID] = s->revision;
     s->regs[GEM_DESCONF] = 0x02500111;
-    s->regs[GEM_DESCONF2] = 0x2ab13fff;
+    s->regs[GEM_DESCONF2] = 0x2ab10000 | s->jumbo_max_len;
     s->regs[GEM_DESCONF5] = 0x002f2045;
     s->regs[GEM_DESCONF6] = GEM_DESCONF6_64B_MASK;
+    s->regs[GEM_JUMBO_MAX_LEN] = s->jumbo_max_len;
 
     if (s->num_priority_queues > 1) {
         queues_mask = MAKE_64BIT_MASK(1, s->num_priority_queues - 1);
@@ -1516,6 +1546,9 @@  static void gem_write(void *opaque, hwaddr offset, uint64_t val,
         s->regs[GEM_IMR] &= ~val;
         gem_update_int_status(s);
         break;
+    case GEM_JUMBO_MAX_LEN:
+        s->regs[GEM_JUMBO_MAX_LEN] = val & MAX_JUMBO_FRAME_SIZE_MASK;
+        break;
     case GEM_INT_Q1_ENABLE ... GEM_INT_Q7_ENABLE:
         s->regs[GEM_INT_Q1_MASK + offset - GEM_INT_Q1_ENABLE] &= ~val;
         gem_update_int_status(s);
@@ -1610,6 +1643,12 @@  static void gem_realize(DeviceState *dev, Error **errp)
 
     s->nic = qemu_new_nic(&net_gem_info, &s->conf,
                           object_get_typename(OBJECT(dev)), dev->id, s);
+
+    if (s->jumbo_max_len > MAX_FRAME_SIZE) {
+        error_setg(errp, "jumbo-max-len is greater than %d",
+                  MAX_FRAME_SIZE);
+        return;
+    }
 }
 
 static void gem_init(Object *obj)
@@ -1659,6 +1698,8 @@  static Property gem_properties[] = {
                       num_type1_screeners, 4),
     DEFINE_PROP_UINT8("num-type2-screeners", CadenceGEMState,
                       num_type2_screeners, 4),
+    DEFINE_PROP_UINT16("jumbo-max-len", CadenceGEMState,
+                       jumbo_max_len, 10240),
     DEFINE_PROP_END_OF_LIST(),
 };
 
diff --git a/include/hw/net/cadence_gem.h b/include/hw/net/cadence_gem.h
index eddac70..54e646f 100644
--- a/include/hw/net/cadence_gem.h
+++ b/include/hw/net/cadence_gem.h
@@ -40,7 +40,8 @@ 
 #define MAX_TYPE1_SCREENERS             16
 #define MAX_TYPE2_SCREENERS             16
 
-#define MAX_FRAME_SIZE 2048
+#define MAX_JUMBO_FRAME_SIZE_MASK 0x3FFF
+#define MAX_FRAME_SIZE MAX_JUMBO_FRAME_SIZE_MASK
 
 typedef struct CadenceGEMState {
     /*< private >*/
@@ -59,6 +60,7 @@  typedef struct CadenceGEMState {
     uint8_t num_type1_screeners;
     uint8_t num_type2_screeners;
     uint32_t revision;
+    uint16_t jumbo_max_len;
 
     /* GEM registers backing store */
     uint32_t regs[CADENCE_GEM_MAXREG];