cryptospore / rpms / qemu-kvm

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From 6bbba130993de09d0623eafe648b978351cb49f9 Mon Sep 17 00:00:00 2001
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From: Xiao Wang <jasowang@redhat.com>
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Date: Thu, 16 Aug 2018 08:17:07 +0100
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Subject: [PATCH 2/4] e1000e: Prevent MSI/MSI-X storms
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RH-Author: Xiao Wang <jasowang@redhat.com>
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Message-id: <1534407427-44794-3-git-send-email-jasowang@redhat.com>
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Patchwork-id: 81853
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O-Subject: [RHEL-8.0 qemu-kvm PATCH 2/2] e1000e: Prevent MSI/MSI-X storms
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Bugzilla: 1596024
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RH-Acked-by: wexu@redhat.com
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RH-Acked-by: Thomas Huth <thuth@redhat.com>
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RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>
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From: Jan Kiszka <jan.kiszka@siemens.com>
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Only signal MSI/MSI-X events on rising edges. So far we re-triggered the
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interrupt sources even if the guest did no consumed the pending one,
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easily causing interrupt storms.
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Issue was observable with Linux 4.16 e1000e driver when MSI-X was used.
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Vector 2 was causing interrupt storms after the driver activated the
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device.
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Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
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Signed-off-by: Jason Wang <jasowang@redhat.com>
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(cherry picked from commit 4712c158c5276fd3c401152f4bb5c3fccf185946)
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Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>
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---
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 hw/net/e1000e_core.c | 11 +++++++++++
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 hw/net/e1000e_core.h |  2 ++
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 2 files changed, 13 insertions(+)
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diff --git a/hw/net/e1000e_core.c b/hw/net/e1000e_core.c
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index 9504891..2a221c2 100644
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--- a/hw/net/e1000e_core.c
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+++ b/hw/net/e1000e_core.c
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@@ -2023,6 +2023,7 @@ e1000e_msix_notify_one(E1000ECore *core, uint32_t cause, uint32_t int_cfg)
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     effective_eiac = core->mac[EIAC] & cause;
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     core->mac[ICR] &= ~effective_eiac;
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+    core->msi_causes_pending &= ~effective_eiac;
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     if (!(core->mac[CTRL_EXT] & E1000_CTRL_EXT_IAME)) {
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         core->mac[IMS] &= ~effective_eiac;
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@@ -2119,6 +2120,13 @@ e1000e_send_msi(E1000ECore *core, bool msix)
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 {
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     uint32_t causes = core->mac[ICR] & core->mac[IMS] & ~E1000_ICR_ASSERTED;
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+    core->msi_causes_pending &= causes;
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+    causes ^= core->msi_causes_pending;
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+    if (causes == 0) {
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+        return;
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+    }
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+    core->msi_causes_pending |= causes;
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+
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     if (msix) {
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         e1000e_msix_notify(core, causes);
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     } else {
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@@ -2156,6 +2164,9 @@ e1000e_update_interrupt_state(E1000ECore *core)
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     core->mac[ICS] = core->mac[ICR];
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     interrupts_pending = (core->mac[IMS] & core->mac[ICR]) ? true : false;
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+    if (!interrupts_pending) {
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+        core->msi_causes_pending = 0;
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+    }
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     trace_e1000e_irq_pending_interrupts(core->mac[ICR] & core->mac[IMS],
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                                         core->mac[ICR], core->mac[IMS]);
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diff --git a/hw/net/e1000e_core.h b/hw/net/e1000e_core.h
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index 7d8ff41..63a1551 100644
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--- a/hw/net/e1000e_core.h
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+++ b/hw/net/e1000e_core.h
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@@ -109,6 +109,8 @@ struct E1000Core {
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     NICState *owner_nic;
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     PCIDevice *owner;
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     void (*owner_start_recv)(PCIDevice *d);
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+
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+    uint32_t msi_causes_pending;
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 };
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 void
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-- 
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1.8.3.1
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