[Xen-devel] [PATCH v4 20/24] arm/acpi: Permit MMIO access of Xen unused devices for Dom0

[Shannon Zhao <zhaoshenglong@xxxxxxxxxx>]

From: Shannon Zhao <shannon.zhao@xxxxxxxxxx>

Firstly it permits full MMIO capabilities for Dom0. Then deny MMIO
access of Xen used devices, such as UART, SMMU. Currently, it only
denies the MMIO access of UART and for other Xen used devices it could
be added later when they are supported.

Signed-off-by: Shannon Zhao <shannon.zhao@xxxxxxxxxx>
---
v4: add comments for TODO
---
 xen/arch/arm/domain_build.c | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index 4aaffae..7750798 100644
--- a/xen/arch/arm/domain_build.c
+++ b/xen/arch/arm/domain_build.c
@@ -1359,6 +1359,33 @@ static int prepare_dtb(struct domain *d, struct 
kernel_info *kinfo)
 #ifdef CONFIG_ACPI
 #define ACPI_DOM0_FDT_MIN_SIZE 4096
 
+static int acpi_iomem_deny_access(struct domain *d)
+{
+    acpi_status status;
+    struct acpi_table_spcr *spcr=NULL;
+    unsigned long gfn;
+    int rc;
+
+    /* Firstly permit full MMIO capabilities. */
+    rc = iomem_permit_access(d, 0UL, ~0UL);
+    if (rc)
+        return rc;
+
+    /* TODO: Deny MMIO access for SMMU, GIC ITS */
+    status = acpi_get_table(ACPI_SIG_SPCR, 0,
+                            (struct acpi_table_header **)&spcr);
+
+    if ( ACPI_FAILURE(status) )
+    {
+        printk("Failed to get SPCR table\n");
+        return -EINVAL;
+    }
+
+    gfn = spcr->serial_port.address >> PAGE_SHIFT;
+    /* Deny MMIO access for UART */
+    return iomem_deny_access(d, gfn, gfn + 1);
+}
+
 static int acpi_permit_spi_access(struct domain *d)
 {
     int i, res;
@@ -1880,6 +1907,10 @@ static int prepare_acpi(struct domain *d, struct 
kernel_info *kinfo)
     if ( rc != 0 )
         return rc;
 
+    rc = acpi_iomem_deny_access(d);
+    if ( rc != 0 )
+        return rc;
+
     return 0;
 }
 #else
-- 
2.0.4



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