[xen staging-4.19] x86/iommu: disable interrupts at shutdown

[patchbot@xxxxxxx]

commit 93302bb88855c5f308f1e67ac2cd84271aa2d73a
Author:     Roger Pau Monné <roger.pau@xxxxxxxxxx>
AuthorDate: Mon Feb 17 13:24:23 2025 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Mon Feb 17 13:24:23 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 92341b7ee7..2cf36cb96c 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 8d6f63d87f..9934316351 100644
--- a/xen/drivers/passthrough/amd/iommu.h
+++ b/xen/drivers/passthrough/amd/iommu.h
@@ -292,6 +292,7 @@ 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);
 
 static inline u32 get_field_from_reg_u32(u32 reg_value, u32 mask, u32 shift)
 {
diff --git a/xen/drivers/passthrough/amd/iommu_init.c 
b/xen/drivers/passthrough/amd/iommu_init.c
index b546c28667..d899f58a38 100644
--- a/xen/drivers/passthrough/amd/iommu_init.c
+++ b/xen/drivers/passthrough/amd/iommu_init.c
@@ -1610,3 +1610,20 @@ 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 f96f59440b..d00697edb3 100644
--- a/xen/drivers/passthrough/amd/pci_amd_iommu.c
+++ b/xen/drivers/passthrough/amd/pci_amd_iommu.c
@@ -791,6 +791,7 @@ 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 50bfd62553..1a3180708c 100644
--- a/xen/drivers/passthrough/iommu.c
+++ b/xen/drivers/passthrough/iommu.c
@@ -662,6 +662,18 @@ 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 ab38bbc8a5..f28de36458 100644
--- a/xen/drivers/passthrough/vtd/iommu.c
+++ b/xen/drivers/passthrough/vtd/iommu.c
@@ -3247,6 +3247,24 @@ 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,
@@ -3276,6 +3294,7 @@ 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 442ae5322d..04f195be04 100644
--- a/xen/include/xen/iommu.h
+++ b/xen/include/xen/iommu.h
@@ -314,6 +314,8 @@ 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);
 };
 
 /*
@@ -404,6 +406,7 @@ 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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