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-rw-r--r--drivers/iommu/intel_irq_remapping.c36
1 files changed, 28 insertions, 8 deletions
diff --git a/drivers/iommu/intel_irq_remapping.c b/drivers/iommu/intel_irq_remapping.c
index 7ca4947c3c10..f3b8f23b5d8f 100644
--- a/drivers/iommu/intel_irq_remapping.c
+++ b/drivers/iommu/intel_irq_remapping.c
@@ -429,11 +429,22 @@ static void iommu_set_irq_remapping(struct intel_iommu *iommu, int mode)
/* Enable interrupt-remapping */
iommu->gcmd |= DMA_GCMD_IRE;
+ iommu->gcmd &= ~DMA_GCMD_CFI; /* Block compatibility-format MSIs */
writel(iommu->gcmd, iommu->reg + DMAR_GCMD_REG);
IOMMU_WAIT_OP(iommu, DMAR_GSTS_REG,
readl, (sts & DMA_GSTS_IRES), sts);
+ /*
+ * With CFI clear in the Global Command register, we should be
+ * protected from dangerous (i.e. compatibility) interrupts
+ * regardless of x2apic status. Check just to be sure.
+ */
+ if (sts & DMA_GSTS_CFIS)
+ WARN(1, KERN_WARNING
+ "Compatibility-format IRQs enabled despite intr remapping;\n"
+ "you are vulnerable to IRQ injection.\n");
+
raw_spin_unlock_irqrestore(&iommu->register_lock, flags);
}
@@ -530,20 +541,24 @@ static int __init intel_irq_remapping_supported(void)
static int __init intel_enable_irq_remapping(void)
{
struct dmar_drhd_unit *drhd;
+ bool x2apic_present;
int setup = 0;
int eim = 0;
+ x2apic_present = x2apic_supported();
+
if (parse_ioapics_under_ir() != 1) {
printk(KERN_INFO "Not enable interrupt remapping\n");
- return -1;
+ goto error;
}
- if (x2apic_supported()) {
+ if (x2apic_present) {
eim = !dmar_x2apic_optout();
- WARN(!eim, KERN_WARNING
- "Your BIOS is broken and requested that x2apic be disabled\n"
- "This will leave your machine vulnerable to irq-injection attacks\n"
- "Use 'intremap=no_x2apic_optout' to override BIOS request\n");
+ if (!eim)
+ printk(KERN_WARNING
+ "Your BIOS is broken and requested that x2apic be disabled.\n"
+ "This will slightly decrease performance.\n"
+ "Use 'intremap=no_x2apic_optout' to override BIOS request.\n");
}
for_each_drhd_unit(drhd) {
@@ -582,7 +597,7 @@ static int __init intel_enable_irq_remapping(void)
if (eim && !ecap_eim_support(iommu->ecap)) {
printk(KERN_INFO "DRHD %Lx: EIM not supported by DRHD, "
" ecap %Lx\n", drhd->reg_base_addr, iommu->ecap);
- return -1;
+ goto error;
}
}
@@ -598,7 +613,7 @@ static int __init intel_enable_irq_remapping(void)
printk(KERN_ERR "DRHD %Lx: failed to enable queued, "
" invalidation, ecap %Lx, ret %d\n",
drhd->reg_base_addr, iommu->ecap, ret);
- return -1;
+ goto error;
}
}
@@ -637,6 +652,11 @@ error:
/*
* handle error condition gracefully here!
*/
+
+ if (x2apic_present)
+ WARN(1, KERN_WARNING
+ "Failed to enable irq remapping. You are vulnerable to irq-injection attacks.\n");
+
return -1;
}