[xen staging] vtd: make sure QI/IR are disabled before initialisation

[patchbot@xxxxxxx]

commit 04181c6fb543db01f635227c7681ced4073109ba
Author:     Igor Druzhinin <igor.druzhinin@xxxxxxxxxx>
AuthorDate: Fri Mar 12 17:01:52 2021 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Fri Mar 12 17:01:52 2021 +0100

    vtd: make sure QI/IR are disabled before initialisation
    
    BIOS might pass control to Xen leaving QI and/or IR in enabled and/or
    partially configured state. In case of x2APIC code path where EIM is
    enabled early in boot - those are correctly disabled by Xen before any
    attempt to configure. But for xAPIC that step is missing which was
    proven to cause QI initialization failures on some ICX based platforms
    where QI is left pre-enabled and partially configured by BIOS. That
    problem becomes hard to avoid since those platforms are shipped with
    x2APIC opt out being advertised by default at the same time by firmware.
    
    Unify the behaviour between x2APIC and xAPIC code paths keeping that in
    line with what Linux does.
    
    Signed-off-by: Igor Druzhinin <igor.druzhinin@xxxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
    Release-Acked-by: Ian Jackson <iwj@xxxxxxxxxxxxxx>
---
 xen/arch/x86/apic.c                 |  2 +-
 xen/drivers/passthrough/vtd/iommu.c | 12 +++++++++++-
 xen/include/asm-x86/apic.h          |  1 +
 3 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/apic.c b/xen/arch/x86/apic.c
index 7497ddb5da..8ab8214559 100644
--- a/xen/arch/x86/apic.c
+++ b/xen/arch/x86/apic.c
@@ -47,7 +47,7 @@ static bool __read_mostly tdt_enabled;
 static bool __initdata tdt_enable = true;
 boolean_param("tdt", tdt_enable);
 
-static bool __read_mostly iommu_x2apic_enabled;
+bool __read_mostly iommu_x2apic_enabled;
 
 static struct {
     int active;
diff --git a/xen/drivers/passthrough/vtd/iommu.c 
b/xen/drivers/passthrough/vtd/iommu.c
index 475efb3be3..9b58d566c8 100644
--- a/xen/drivers/passthrough/vtd/iommu.c
+++ b/xen/drivers/passthrough/vtd/iommu.c
@@ -2101,7 +2101,7 @@ static int __must_check init_vtd_hw(void)
     u32 sts;
 
     /*
-     * Basic VT-d HW init: set VT-d interrupt, clear VT-d faults.  
+     * Basic VT-d HW init: set VT-d interrupt, clear VT-d faults, etc.
      */
     for_each_drhd_unit ( drhd )
     {
@@ -2111,6 +2111,16 @@ static int __must_check init_vtd_hw(void)
 
         clear_fault_bits(iommu);
 
+        /*
+         * Disable interrupt remapping and queued invalidation if
+         * already enabled by BIOS in case we've not initialized it yet.
+         */
+        if ( !iommu_x2apic_enabled )
+        {
+            disable_intremap(iommu);
+            disable_qinval(iommu);
+        }
+
         spin_lock_irqsave(&iommu->register_lock, flags);
         sts = dmar_readl(iommu->reg, DMAR_FECTL_REG);
         sts &= ~DMA_FECTL_IM;
diff --git a/xen/include/asm-x86/apic.h b/xen/include/asm-x86/apic.h
index 8ddb896ee9..2fe54bbf1c 100644
--- a/xen/include/asm-x86/apic.h
+++ b/xen/include/asm-x86/apic.h
@@ -24,6 +24,7 @@ enum apic_mode {
     APIC_MODE_X2APIC    /* x2APIC mode - common for large MP machines */
 };
 
+extern bool iommu_x2apic_enabled;
 extern u8 apic_verbosity;
 extern bool directed_eoi_enabled;
 
--
generated by git-patchbot for /home/xen/git/xen.git#staging