[xen staging-4.18] x86/iommu: disable interrupts at shutdown

[patchbot@xxxxxxx]

commit 63866198f57ba33f1040d5c92c7bdf0b925b0ba4
Author:     Roger Pau Monné <roger.pau@xxxxxxxxxx>
AuthorDate: Mon Feb 17 13:33:12 2025 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Mon Feb 17 13:33:12 2025 +0100

    x86/iommu: disable interrupts at shutdown
    
    Add a new hook to inhibit interrupt generation by the IOMMU(s).  Note the
    hook is currently only implemented for x86 IOMMUs.  The purpose is to
    disable interrupt generation at shutdown so any kexec chained image finds
    the IOMMU(s) in a quiesced state.
    
    It would also prevent "Receive accept error" being raised as a result of
    non-disabled interrupts targeting offline CPUs.
    
    Note that the iommu_quiesce() call in nmi_shootdown_cpus() is still
    required even when there's a preceding iommu_crash_shutdown() call; the
    later can become a no-op depending on the setting of the "crash-disable"
    command line option.
    
    Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
    master commit: 819c3cb186a86ef3e04fb5af4d9f9f6de032c3ee
    master date: 2025-02-12 15:56:07 +0100
---
 xen/arch/x86/crash.c                        |  1 +
 xen/arch/x86/smp.c                          |  1 +
 xen/drivers/passthrough/amd/iommu.h         |  1 +
 xen/drivers/passthrough/amd/iommu_init.c    | 17 +++++++++++++++++
 xen/drivers/passthrough/amd/pci_amd_iommu.c |  1 +
 xen/drivers/passthrough/iommu.c             | 12 ++++++++++++
 xen/drivers/passthrough/vtd/iommu.c         | 19 +++++++++++++++++++
 xen/include/xen/iommu.h                     |  3 +++
 8 files changed, 55 insertions(+)

diff --git a/xen/arch/x86/crash.c b/xen/arch/x86/crash.c
index 22b1121d7a..26057c71d3 100644
--- a/xen/arch/x86/crash.c
+++ b/xen/arch/x86/crash.c
@@ -187,6 +187,7 @@ static void nmi_shootdown_cpus(void)
 
         disable_IO_APIC();
         hpet_disable();
+        iommu_quiesce();
     }
 }
 
diff --git a/xen/arch/x86/smp.c b/xen/arch/x86/smp.c
index 3b79436b31..1f86ed4f4c 100644
--- a/xen/arch/x86/smp.c
+++ b/xen/arch/x86/smp.c
@@ -375,6 +375,7 @@ void smp_send_stop(void)
     pci_disable_msi_all();
     disable_IO_APIC();
     hpet_disable();
+    iommu_quiesce();
 
     if ( num_online_cpus() > 1 )
     {
diff --git a/xen/drivers/passthrough/amd/iommu.h 
b/xen/drivers/passthrough/amd/iommu.h
index d4416ebc43..551bc6c10c 100644
--- a/xen/drivers/passthrough/amd/iommu.h
+++ b/xen/drivers/passthrough/amd/iommu.h
@@ -340,6 +340,7 @@ extern unsigned long *shared_intremap_inuse;
 void cf_check amd_iommu_resume(void);
 int __must_check cf_check amd_iommu_suspend(void);
 void cf_check amd_iommu_crash_shutdown(void);
+void cf_check amd_iommu_quiesce(void);
 
 /* guest iommu support */
 #ifdef CONFIG_HVM
diff --git a/xen/drivers/passthrough/amd/iommu_init.c 
b/xen/drivers/passthrough/amd/iommu_init.c
index d672e682f8..1388f112d5 100644
--- a/xen/drivers/passthrough/amd/iommu_init.c
+++ b/xen/drivers/passthrough/amd/iommu_init.c
@@ -1606,3 +1606,20 @@ void cf_check amd_iommu_resume(void)
         invalidate_all_domain_pages();
     }
 }
+
+void cf_check amd_iommu_quiesce(void)
+{
+    struct amd_iommu *iommu;
+
+    for_each_amd_iommu ( iommu )
+    {
+        if ( iommu->ctrl.int_cap_xt_en )
+        {
+            iommu->ctrl.int_cap_xt_en = false;
+            writeq(iommu->ctrl.raw,
+                   iommu->mmio_base + IOMMU_CONTROL_MMIO_OFFSET);
+        }
+        else
+            amd_iommu_msi_enable(iommu, IOMMU_CONTROL_DISABLED);
+    }
+}
diff --git a/xen/drivers/passthrough/amd/pci_amd_iommu.c 
b/xen/drivers/passthrough/amd/pci_amd_iommu.c
index 40a56008aa..37ba23ac2d 100644
--- a/xen/drivers/passthrough/amd/pci_amd_iommu.c
+++ b/xen/drivers/passthrough/amd/pci_amd_iommu.c
@@ -784,6 +784,7 @@ static const struct iommu_ops __initconst_cf_clobber 
_iommu_ops = {
     .crash_shutdown = amd_iommu_crash_shutdown,
     .get_reserved_device_memory = amd_iommu_get_reserved_device_memory,
     .dump_page_tables = amd_dump_page_tables,
+    .quiesce = amd_iommu_quiesce,
 };
 
 static const struct iommu_init_ops __initconstrel _iommu_init_ops = {
diff --git a/xen/drivers/passthrough/iommu.c b/xen/drivers/passthrough/iommu.c
index f9a9f53dbd..46874d6c56 100644
--- a/xen/drivers/passthrough/iommu.c
+++ b/xen/drivers/passthrough/iommu.c
@@ -658,6 +658,18 @@ void iommu_crash_shutdown(void)
 #endif
 }
 
+void iommu_quiesce(void)
+{
+    const struct iommu_ops *ops;
+
+    if ( !iommu_enabled )
+        return;
+
+    ops = iommu_get_ops();
+    if ( ops->quiesce )
+        iommu_vcall(ops, quiesce);
+}
+
 int iommu_get_reserved_device_memory(iommu_grdm_t *func, void *ctxt)
 {
     const struct iommu_ops *ops;
diff --git a/xen/drivers/passthrough/vtd/iommu.c 
b/xen/drivers/passthrough/vtd/iommu.c
index a6f0071fe9..5f9906a290 100644
--- a/xen/drivers/passthrough/vtd/iommu.c
+++ b/xen/drivers/passthrough/vtd/iommu.c
@@ -3241,6 +3241,24 @@ static int cf_check intel_iommu_quarantine_init(struct 
pci_dev *pdev,
     return rc;
 }
 
+static void cf_check vtd_quiesce(void)
+{
+    const struct acpi_drhd_unit *drhd;
+
+    for_each_drhd_unit ( drhd )
+    {
+        const struct vtd_iommu *iommu = drhd->iommu;
+        uint32_t sts = dmar_readl(iommu->reg, DMAR_FECTL_REG);
+
+        /*
+         * Open code dma_msi_mask() to avoid taking the spinlock which could
+         * deadlock if called from crash context.
+         */
+        sts |= DMA_FECTL_IM;
+        dmar_writel(iommu->reg, DMAR_FECTL_REG, sts);
+    }
+}
+
 static const struct iommu_ops __initconst_cf_clobber vtd_ops = {
     .page_sizes = PAGE_SIZE_4K,
     .init = intel_iommu_domain_init,
@@ -3270,6 +3288,7 @@ static const struct iommu_ops __initconst_cf_clobber 
vtd_ops = {
     .iotlb_flush = iommu_flush_iotlb,
     .get_reserved_device_memory = intel_iommu_get_reserved_device_memory,
     .dump_page_tables = vtd_dump_page_tables,
+    .quiesce = vtd_quiesce,
 };
 
 const struct iommu_init_ops __initconstrel intel_iommu_init_ops = {
diff --git a/xen/include/xen/iommu.h b/xen/include/xen/iommu.h
index 0e747b0bbc..e9296e36ee 100644
--- a/xen/include/xen/iommu.h
+++ b/xen/include/xen/iommu.h
@@ -320,6 +320,8 @@ struct iommu_ops {
      */
     int (*dt_xlate)(device_t *dev, const struct dt_phandle_args *args);
 #endif
+    /* Inhibit all interrupt generation, to be used at shutdown. */
+    void (*quiesce)(void);
 };
 
 /*
@@ -400,6 +402,7 @@ static inline int iommu_do_domctl(struct xen_domctl 
*domctl, struct domain *d,
 int __must_check iommu_suspend(void);
 void iommu_resume(void);
 void iommu_crash_shutdown(void);
+void iommu_quiesce(void);
 int iommu_get_reserved_device_memory(iommu_grdm_t *func, void *ctxt);
 int iommu_quarantine_dev_init(device_t *dev);
 
--
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