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Message-Id: <573BDCBC-3C4F-4A41-91D8-60BD7C44C43E@oracle.com>
Date: Thu, 20 Feb 2020 10:26:37 -0600
From: John Donnelly <john.p.donnelly@...cle.com>
To: linux-kernel@...r.kernel.org
Subject: [PATCH] iommu: Force iommu shutdown on panic.
This eliminates intermitten kdump hangs reported on AMD/x86 servers
with iommu enabled (iommu=on) regardless if iommu features are
used or not, on 5.4 kernels. When kdump fails to initialize and run, no vmcore
(crash dumps) are captured.
Derived from the upsteam commit: iommu/vt-d: Turn off translations at shutdown.
Signed-off-by: John Donnelly <john.p.donnelly@...cle.com>
Reviewed-by: Jack Vogel <jack.vogel@...cle.com>
---
arch/x86/include/asm/x86_init.h | 2 +-
arch/x86/kernel/amd_gart_64.c | 2 +-
arch/x86/kernel/reboot.c | 2 +-
arch/x86/kernel/x86_init.c | 2 +-
drivers/iommu/amd_iommu_init.c | 8 ++++----
drivers/iommu/intel-iommu.c | 9 ++++++---
include/linux/dmar.h | 4 ++--
kernel/panic.c | 7 +++++++
8 files changed, 23 insertions(+), 13 deletions(-)
diff --git a/arch/x86/include/asm/x86_init.h b/arch/x86/include/asm/x86_init.h
index 96d9cd208610..06233f57b7c9 100644
--- a/arch/x86/include/asm/x86_init.h
+++ b/arch/x86/include/asm/x86_init.h
@@ -270,7 +270,7 @@ struct x86_platform_ops {
unsigned long (*calibrate_tsc)(void);
void (*get_wallclock)(struct timespec64 *ts);
int (*set_wallclock)(const struct timespec64 *ts);
- void (*iommu_shutdown)(void);
+ void (*iommu_shutdown)(int panic);
bool (*is_untracked_pat_range)(u64 start, u64 end);
void (*nmi_init)(void);
unsigned char (*get_nmi_reason)(void);
diff --git a/arch/x86/kernel/amd_gart_64.c b/arch/x86/kernel/amd_gart_64.c
index 4e5f50236048..2f805cc073ad 100644
--- a/arch/x86/kernel/amd_gart_64.c
+++ b/arch/x86/kernel/amd_gart_64.c
@@ -681,7 +681,7 @@ static const struct dma_map_ops gart_dma_ops = {
.get_required_mask = dma_direct_get_required_mask,
};
-static void gart_iommu_shutdown(void)
+static void gart_iommu_shutdown(int panic)
{
struct pci_dev *dev;
int i;
diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c
index 0cc7c0b106bb..fd3c88a4f2e7 100644
--- a/arch/x86/kernel/reboot.c
+++ b/arch/x86/kernel/reboot.c
@@ -708,7 +708,7 @@ void native_machine_shutdown(void)
#endif
#ifdef CONFIG_X86_64
- x86_platform.iommu_shutdown();
+ x86_platform.iommu_shutdown(0);
#endif
}
diff --git a/arch/x86/kernel/x86_init.c b/arch/x86/kernel/x86_init.c
index 85f1a90c55cd..e63719710097 100644
--- a/arch/x86/kernel/x86_init.c
+++ b/arch/x86/kernel/x86_init.c
@@ -28,7 +28,7 @@
void x86_init_noop(void) { }
void __init x86_init_uint_noop(unsigned int unused) { }
static int __init iommu_init_noop(void) { return 0; }
-static void iommu_shutdown_noop(void) { }
+static void iommu_shutdown_noop(int panic) { }
bool __init bool_x86_init_noop(void) { return false; }
void x86_op_int_noop(int cpu) { }
static __init int set_rtc_noop(const struct timespec64 *now) { return -EINVAL; }
diff --git a/drivers/iommu/amd_iommu_init.c b/drivers/iommu/amd_iommu_init.c
index 2759a8d57b7f..a1afc2e2a68c 100644
--- a/drivers/iommu/amd_iommu_init.c
+++ b/drivers/iommu/amd_iommu_init.c
@@ -2361,7 +2361,7 @@ static void enable_iommus(void)
enable_iommus_v2();
}
-static void disable_iommus(void)
+static void disable_iommus(int panic)
{
struct amd_iommu *iommu;
@@ -2395,7 +2395,7 @@ static void amd_iommu_resume(void)
static int amd_iommu_suspend(void)
{
/* disable IOMMUs to go out of the way for BIOS */
- disable_iommus();
+ disable_iommus(0);
return 0;
}
@@ -2612,7 +2612,7 @@ static int __init early_amd_iommu_init(void)
/* Disable any previously enabled IOMMUs */
if (!is_kdump_kernel() || amd_iommu_disabled)
- disable_iommus();
+ disable_iommus(0);
if (amd_iommu_irq_remap)
amd_iommu_irq_remap = check_ioapic_information();
@@ -2762,7 +2762,7 @@ static int __init state_next(void)
if (ret) {
free_dma_resources();
if (!irq_remapping_enabled) {
- disable_iommus();
+ disable_iommus(0);
free_iommu_resources();
} else {
struct amd_iommu *iommu;
diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 9dc37672bf89..8bc95f4e7d3e 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -4903,7 +4903,7 @@ static void intel_disable_iommus(void)
iommu_disable_translation(iommu);
}
-void intel_iommu_shutdown(void)
+void intel_iommu_shutdown(int panic)
{
struct dmar_drhd_unit *drhd;
struct intel_iommu *iommu = NULL;
@@ -4911,7 +4911,8 @@ void intel_iommu_shutdown(void)
if (no_iommu || dmar_disabled)
return;
- down_write(&dmar_global_lock);
+ if (!panic)
+ down_write(&dmar_global_lock);
/* Disable PMRs explicitly here. */
for_each_iommu(iommu, drhd)
@@ -4920,7 +4921,9 @@ void intel_iommu_shutdown(void)
/* Make sure the IOMMUs are switched off */
intel_disable_iommus();
- up_write(&dmar_global_lock);
+ if (!panic)
+ up_write(&dmar_global_lock);
+
}
static inline struct intel_iommu *dev_to_intel_iommu(struct device *dev)
diff --git a/include/linux/dmar.h b/include/linux/dmar.h
index f64ca27dc210..c4f24bc41169 100644
--- a/include/linux/dmar.h
+++ b/include/linux/dmar.h
@@ -129,7 +129,7 @@ static inline int dmar_res_noop(struct acpi_dmar_header *hdr, void *arg)
#ifdef CONFIG_INTEL_IOMMU
extern int iommu_detected, no_iommu;
extern int intel_iommu_init(void);
-extern void intel_iommu_shutdown(void);
+extern void intel_iommu_shutdown(int panic);
extern int dmar_parse_one_rmrr(struct acpi_dmar_header *header, void *arg);
extern int dmar_parse_one_atsr(struct acpi_dmar_header *header, void *arg);
extern int dmar_check_one_atsr(struct acpi_dmar_header *hdr, void *arg);
@@ -138,7 +138,7 @@ extern int dmar_iommu_hotplug(struct dmar_drhd_unit *dmaru, bool insert);
extern int dmar_iommu_notify_scope_dev(struct dmar_pci_notify_info *info);
#else /* !CONFIG_INTEL_IOMMU: */
static inline int intel_iommu_init(void) { return -ENODEV; }
-static inline void intel_iommu_shutdown(void) { }
+static inline void intel_iommu_shutdown(int panic) { }
#define dmar_parse_one_rmrr dmar_res_noop
#define dmar_parse_one_atsr dmar_res_noop
diff --git a/kernel/panic.c b/kernel/panic.c
index b69ee9e76cb2..ee81462d5b1f 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -32,6 +32,7 @@
#include <linux/ratelimit.h>
#include <linux/debugfs.h>
#include <asm/sections.h>
+#include <linux/dmar.h>
#define PANIC_TIMER_STEP 100
#define PANIC_BLINK_SPD 18
@@ -213,6 +214,12 @@ void panic(const char *fmt, ...)
buf[len - 1] = '\0';
pr_emerg("Kernel panic - not syncing: %s\n", buf);
+
+#ifdef CONFIG_X86
+ pr_emerg("Shutting down iommu.\n");
+ x86_platform.iommu_shutdown(1);
+#endif
+
#ifdef CONFIG_DEBUG_BUGVERBOSE
/*
* Avoid nested stack-dumping if a panic occurs during oops processing
--
2.20.1
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