Re: [dpdk-stable] [PATCH] net/i40e: fix counters

["Guo, Jia" <jia.guo@intel.com>]

hi, igor ryzhov and Thomas

Since this remain issue is report recently and we need to reproduce the issue and evaluate the patch and guaranty no side affect for other case,
so I am not sure even I don't think it still have time window to hit 20.11. But whatever we have begin to check your patch for now on. What do you think so?


From: Igor Ryzhov <iryzhov@nfware.com>
Sent: Friday, November 20, 2020 2:27 AM
To: dev <dev@dpdk.org>
Cc: dpdk stable <stable@dpdk.org>; Xing, Beilei <beilei.xing@intel.com>; Guo, Jia <jia.guo@intel.com>; Thomas Monjalon <thomas@monjalon.net>
Subject: Re: [PATCH] net/i40e: fix counters

CC maintainers and Thomas.

This fix should be 20.11. The issue is seen multiple times a day under ~20G traffic with stats collection once per second.

Igor

On Tue, Nov 17, 2020 at 11:56 AM Igor Ryzhov <iryzhov@nfware.com<mailto:iryzhov@nfware.com>> wrote:
When low and high registers are read separately, this opens the door to
a race condition:
- low register is read
- NIC updates the registers
- high register is read

Because of this, we may end up with an incorrect counter value.
Let's read the registers in one shot, as it is done in Linux kernel
since the introduction of the i40e driver.

Fixes: 4861cde46116 ("i40e: new poll mode driver")
Cc: stable@dpdk.org<mailto:stable@dpdk.org>
Signed-off-by: Igor Ryzhov <iryzhov@nfware.com<mailto:iryzhov@nfware.com>>
---
 drivers/net/i40e/base/i40e_osdep.h | 10 ++++++++++
 drivers/net/i40e/i40e_ethdev.c     | 10 +++++++---
 2 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/drivers/net/i40e/base/i40e_osdep.h b/drivers/net/i40e/base/i40e_osdep.h
index 64b15e1b6138..ebd687240006 100644
--- a/drivers/net/i40e/base/i40e_osdep.h
+++ b/drivers/net/i40e/base/i40e_osdep.h
@@ -133,6 +133,14 @@ static inline uint32_t i40e_read_addr(volatile void *addr)
        return rte_le_to_cpu_32(I40E_PCI_REG(addr));
 }

+#define I40E_PCI_REG64(reg)            rte_read64(reg)
+#define I40E_PCI_REG64_ADDR(a, reg) \
+       ((volatile uint64_t *)((char *)(a)->hw_addr + (reg)))
+static inline uint64_t i40e_read64_addr(volatile void *addr)
+{
+       return rte_le_to_cpu_64(I40E_PCI_REG64(addr));
+}
+
 #define I40E_PCI_REG_WRITE(reg, value)         \
        rte_write32((rte_cpu_to_le_32(value)), reg)
 #define I40E_PCI_REG_WRITE_RELAXED(reg, value) \
@@ -145,6 +153,8 @@ static inline uint32_t i40e_read_addr(volatile void *addr)
 #define I40E_WRITE_REG(hw, reg, value) \
        I40E_PCI_REG_WRITE(I40E_PCI_REG_ADDR((hw), (reg)), (value))

+#define I40E_READ_REG64(hw, reg) i40e_read64_addr(I40E_PCI_REG64_ADDR((hw), (reg)))
+
 #define rd32(a, reg) i40e_read_addr(I40E_PCI_REG_ADDR((a), (reg)))
 #define wr32(a, reg, value) \
        I40E_PCI_REG_WRITE(I40E_PCI_REG_ADDR((a), (reg)), (value))
diff --git a/drivers/net/i40e/i40e_ethdev.c b/drivers/net/i40e/i40e_ethdev.c
index 74f4ac1f9d4e..53b1e9b9e067 100644
--- a/drivers/net/i40e/i40e_ethdev.c
+++ b/drivers/net/i40e/i40e_ethdev.c
@@ -6451,9 +6451,13 @@ i40e_stat_update_48(struct i40e_hw *hw,
 {
        uint64_t new_data;

-       new_data = (uint64_t)I40E_READ_REG(hw, loreg);
-       new_data |= ((uint64_t)(I40E_READ_REG(hw, hireg) &
-                       I40E_16_BIT_MASK)) << I40E_32_BIT_WIDTH;
+       if (hw->device_id == I40E_DEV_ID_QEMU) {
+               new_data = (uint64_t)I40E_READ_REG(hw, loreg);
+               new_data |= ((uint64_t)(I40E_READ_REG(hw, hireg) &
+                               I40E_16_BIT_MASK)) << I40E_32_BIT_WIDTH;
+       } else {
+               new_data = I40E_READ_REG64(hw, loreg);
+       }

        if (!offset_loaded)
                *offset = new_data;
--
2.29.2