[xen staging] xen/arm: acpi: Don't fail if SPCR table is absent

[patchbot@xxxxxxx]

commit 861f0c110976fa8879b7bf63d9478b6be83d4ab6
Author:     Elliott Mitchell <ehem+xen@xxxxxxx>
AuthorDate: Wed Oct 21 15:12:53 2020 -0700
Commit:     Julien Grall <jgrall@xxxxxxxxxx>
CommitDate: Thu Oct 22 19:41:51 2020 +0100

    xen/arm: acpi: Don't fail if SPCR table is absent
    
    Absence of a SPCR table likely means the console is a framebuffer.  In
    such case acpi_iomem_deny_access() should NOT fail.
    
    Signed-off-by: Elliott Mitchell <ehem+xen@xxxxxxx>
    Acked-by: Julien Grall <jgrall@xxxxxxxxxx>
    Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>
---
 xen/arch/arm/acpi/domain_build.c | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/xen/arch/arm/acpi/domain_build.c b/xen/arch/arm/acpi/domain_build.c
index 1b1cfabb00..bbdc90f92c 100644
--- a/xen/arch/arm/acpi/domain_build.c
+++ b/xen/arch/arm/acpi/domain_build.c
@@ -42,17 +42,18 @@ static int __init acpi_iomem_deny_access(struct domain *d)
     status = acpi_get_table(ACPI_SIG_SPCR, 0,
                             (struct acpi_table_header **)&spcr);
 
-    if ( ACPI_FAILURE(status) )
+    if ( ACPI_SUCCESS(status) )
     {
-        printk("Failed to get SPCR table\n");
-        return -EINVAL;
+        mfn = spcr->serial_port.address >> PAGE_SHIFT;
+        /* Deny MMIO access for UART */
+        rc = iomem_deny_access(d, mfn, mfn + 1);
+        if ( rc )
+            return rc;
+    }
+    else
+    {
+        printk("Failed to get SPCR table, Xen console may be unavailable\n");
     }
-
-    mfn = spcr->serial_port.address >> PAGE_SHIFT;
-    /* Deny MMIO access for UART */
-    rc = iomem_deny_access(d, mfn, mfn + 1);
-    if ( rc )
-        return rc;
 
     /* Deny MMIO access for GIC regions */
     return gic_iomem_deny_access(d);
--
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