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dmar: Disable PMR in driver attach routine

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Previously it was disabled right before translation was enabled.
This way the disable logic is still executed even when translation
is not be activated, e.g. with hw.iommu.dma=0 tunable set.
On some platforms we need to disable PMR in order for core dump to work.
At the same time it was observed that enabling translation has
a significant impact on network performance.
With this patch PMR can be disabled, with IOMMU translation not being
turned on by appending the following to the loader.conf:

hw.dmar.enable=1
hw.dmar.pmr.disable=1
hw.dmar.dma=0

Sponsored by: Stormshield
Obtained from: Semihalf
Reviewed by: kib
Differential Revision: https://reviews.freebsd.org/D34907
This commit is contained in:
Kornel Duleba 2022-04-14 12:55:53 +02:00 committed by Wojciech Macek
parent 14b7706264
commit 06f659c39d
2 changed files with 14 additions and 0 deletions
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11
sys/x86/iommu/intel_drv.c
View File

@ -405,6 +405,7 @@ dmar_attach(device_t dev)
struct dmar_unit *unit;
ACPI_DMAR_HARDWARE_UNIT *dmaru;
uint64_t timeout;
int disable_pmr;
int i, error;
unit = device_get_softc(dev);
@ -528,6 +529,16 @@ dmar_attach(device_t dev)
dmar_release_resources(dev, unit);
return (error);
}
disable_pmr = 0;
TUNABLE_INT_FETCH("hw.dmar.pmr.disable", &disable_pmr);
if (disable_pmr) {
error = dmar_disable_protected_regions(unit);
if (error != 0)
device_printf(dev,
"Failed to disable protected regions\n");
}
error = iommu_init_busdma(&unit->iommu);
if (error != 0) {
dmar_release_resources(dev, unit);

3
sys/x86/iommu/intel_utils.c
View File

@ -508,6 +508,9 @@ dmar_disable_protected_regions(struct dmar_unit *unit)
return (0);
reg = dmar_read4(unit, DMAR_PMEN_REG);
if ((reg & DMAR_PMEN_EPM) == 0)
return (0);
reg &= ~DMAR_PMEN_EPM;
dmar_write4(unit, DMAR_PMEN_REG, reg);
DMAR_WAIT_UNTIL(((dmar_read4(unit, DMAR_PMEN_REG) & DMAR_PMEN_PRS)