[v3,17/26] hw/arm/virt: Reserve one bit of guest-physical address for RME

Commit Message

Jean-Philippe Brucker Nov. 25, 2024, 7:56 p.m. UTC

When RME is enabled, the upper GPA bit is used to distinguish protected
from unprotected addresses. Reserve it when setting up the guest memory
map.

Signed-off-by: Jean-Philippe Brucker <[e-mail]>
---
 hw/arm/virt.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

Patch

diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index 9836dfbdfb..eb94997914 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -3035,14 +3035,24 @@  static int virt_kvm_type(MachineState *ms, const char *type_str)
     VirtMachineState *vms = VIRT_MACHINE(ms);
     int rme_vm_type = kvm_arm_rme_vm_type(ms);
     int max_vm_pa_size, requested_pa_size;
+    int rme_reserve_bit = 0;
     bool fixed_ipa;
 
-    max_vm_pa_size = kvm_arm_get_max_vm_ipa_size(ms, &fixed_ipa);
+    if (rme_vm_type) {
+        /*
+         * With RME, the upper GPA bit differentiates Realm from NS memory.
+         * Reserve the upper bit to ensure that highmem devices will fit.
+         */
+        rme_reserve_bit = 1;
+    }
+
+    max_vm_pa_size = kvm_arm_get_max_vm_ipa_size(ms, &fixed_ipa) -
+                     rme_reserve_bit;
 
     /* we freeze the memory map to compute the highest gpa */
     virt_set_memmap(vms, max_vm_pa_size);
 
-    requested_pa_size = 64 - clz64(vms->highest_gpa);
+    requested_pa_size = 64 - clz64(vms->highest_gpa) + rme_reserve_bit;
 
     /*
      * KVM requires the IPA size to be at least 32 bits.