Patchwork e1000: Mask out lower bits of RDBAL/TDBAL

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Submitter Kevin Wolf
Date March 26, 2011, 6:37 p.m.
Message ID <1301164676-27078-1-git-send-email-mail@kevin-wolf.de>
Download mbox | patch
Permalink /patch/88475/
State New
Headers show

Comments

Kevin Wolf - March 26, 2011, 6:37 p.m.
Rx and Tx descriptors are 16 byte aligned, so the lower bits are
ignored by real hardware. In fact, they always read back as zero on real
hardware, but probably nobody relies on that.

Signed-off-by: Kevin Wolf <mail@kevin-wolf.de>
---
 hw/e1000.c |   21 ++++++++++++++++++---
 1 files changed, 18 insertions(+), 3 deletions(-)
Aurelien Jarno - April 3, 2011, 10:15 p.m.
On Sat, Mar 26, 2011 at 07:37:56PM +0100, Kevin Wolf wrote:
> Rx and Tx descriptors are 16 byte aligned, so the lower bits are
> ignored by real hardware. In fact, they always read back as zero on real
> hardware, but probably nobody relies on that.
> 
> Signed-off-by: Kevin Wolf <mail@kevin-wolf.de>
> ---
>  hw/e1000.c |   21 ++++++++++++++++++---
>  1 files changed, 18 insertions(+), 3 deletions(-)

Thanks, applied.

> diff --git a/hw/e1000.c b/hw/e1000.c
> index 2a4d5c7..a65fc7a 100644
> --- a/hw/e1000.c
> +++ b/hw/e1000.c
> @@ -517,6 +517,14 @@ txdesc_writeback(target_phys_addr_t base, struct e1000_tx_desc *dp)
>      return E1000_ICR_TXDW;
>  }
>  
> +static uint64_t tx_desc_base(E1000State *s)
> +{
> +    uint64_t bah = s->mac_reg[TDBAH];
> +    uint64_t bal = s->mac_reg[TDBAL] & ~0xf;
> +
> +    return (bah << 32) + bal;
> +}
> +
>  static void
>  start_xmit(E1000State *s)
>  {
> @@ -530,7 +538,7 @@ start_xmit(E1000State *s)
>      }
>  
>      while (s->mac_reg[TDH] != s->mac_reg[TDT]) {
> -        base = ((uint64_t)s->mac_reg[TDBAH] << 32) + s->mac_reg[TDBAL] +
> +        base = tx_desc_base(s) +
>                 sizeof(struct e1000_tx_desc) * s->mac_reg[TDH];
>          cpu_physical_memory_read(base, (void *)&desc, sizeof(desc));
>  
> @@ -651,6 +659,14 @@ static bool e1000_has_rxbufs(E1000State *s, size_t total_size)
>      return total_size <= bufs * s->rxbuf_size;
>  }
>  
> +static uint64_t rx_desc_base(E1000State *s)
> +{
> +    uint64_t bah = s->mac_reg[RDBAH];
> +    uint64_t bal = s->mac_reg[RDBAL] & ~0xf;
> +
> +    return (bah << 32) + bal;
> +}
> +
>  static ssize_t
>  e1000_receive(VLANClientState *nc, const uint8_t *buf, size_t size)
>  {
> @@ -700,8 +716,7 @@ e1000_receive(VLANClientState *nc, const uint8_t *buf, size_t size)
>          if (desc_size > s->rxbuf_size) {
>              desc_size = s->rxbuf_size;
>          }
> -        base = ((uint64_t)s->mac_reg[RDBAH] << 32) + s->mac_reg[RDBAL] +
> -               sizeof(desc) * s->mac_reg[RDH];
> +        base = rx_desc_base(s) + sizeof(desc) * s->mac_reg[RDH];
>          cpu_physical_memory_read(base, (void *)&desc, sizeof(desc));
>          desc.special = vlan_special;
>          desc.status |= (vlan_status | E1000_RXD_STAT_DD);
> -- 
> 1.6.0.2
> 
> 
>

Patch

diff --git a/hw/e1000.c b/hw/e1000.c
index 2a4d5c7..a65fc7a 100644
--- a/hw/e1000.c
+++ b/hw/e1000.c
@@ -517,6 +517,14 @@  txdesc_writeback(target_phys_addr_t base, struct e1000_tx_desc *dp)
     return E1000_ICR_TXDW;
 }
 
+static uint64_t tx_desc_base(E1000State *s)
+{
+    uint64_t bah = s->mac_reg[TDBAH];
+    uint64_t bal = s->mac_reg[TDBAL] & ~0xf;
+
+    return (bah << 32) + bal;
+}
+
 static void
 start_xmit(E1000State *s)
 {
@@ -530,7 +538,7 @@  start_xmit(E1000State *s)
     }
 
     while (s->mac_reg[TDH] != s->mac_reg[TDT]) {
-        base = ((uint64_t)s->mac_reg[TDBAH] << 32) + s->mac_reg[TDBAL] +
+        base = tx_desc_base(s) +
                sizeof(struct e1000_tx_desc) * s->mac_reg[TDH];
         cpu_physical_memory_read(base, (void *)&desc, sizeof(desc));
 
@@ -651,6 +659,14 @@  static bool e1000_has_rxbufs(E1000State *s, size_t total_size)
     return total_size <= bufs * s->rxbuf_size;
 }
 
+static uint64_t rx_desc_base(E1000State *s)
+{
+    uint64_t bah = s->mac_reg[RDBAH];
+    uint64_t bal = s->mac_reg[RDBAL] & ~0xf;
+
+    return (bah << 32) + bal;
+}
+
 static ssize_t
 e1000_receive(VLANClientState *nc, const uint8_t *buf, size_t size)
 {
@@ -700,8 +716,7 @@  e1000_receive(VLANClientState *nc, const uint8_t *buf, size_t size)
         if (desc_size > s->rxbuf_size) {
             desc_size = s->rxbuf_size;
         }
-        base = ((uint64_t)s->mac_reg[RDBAH] << 32) + s->mac_reg[RDBAL] +
-               sizeof(desc) * s->mac_reg[RDH];
+        base = rx_desc_base(s) + sizeof(desc) * s->mac_reg[RDH];
         cpu_physical_memory_read(base, (void *)&desc, sizeof(desc));
         desc.special = vlan_special;
         desc.status |= (vlan_status | E1000_RXD_STAT_DD);