[PATCH v2 3/5] hw/arm/virt: Honor highmem setting when computing the memory map

From: Marc Zyngier <maz@kernel.org>
To: qemu-devel@nongnu.org
Cc: Andrew Jones <drjones@redhat.com>,
	Eric Auger <eric.auger@redhat.com>,
	Peter Maydell <peter.maydell@linaro.org>,
	kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org,
	kernel-team@android.com
Subject: [PATCH v2 3/5] hw/arm/virt: Honor highmem setting when computing the memory map
Date: Sun,  3 Oct 2021 17:46:03 +0100	[thread overview]
Message-ID: <20211003164605.3116450-4-maz@kernel.org> (raw)
In-Reply-To: <20211003164605.3116450-1-maz@kernel.org>

Even when the VM is configured with highmem=off, the highest_gpa
field includes devices that are above the 4GiB limit.
Similarily, nothing seem to check that the memory is within
the limit set by the highmem=off option.

This leads to failures in virt_kvm_type() on systems that have
a crippled IPA range, as the reported IPA space is larger than
what it should be.

Instead, honor the user-specified limit to only use the devices
at the lowest end of the spectrum, and fail if we have memory
crossing the 4GiB limit.

Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 hw/arm/virt.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index bcf58f677d..9d2abdbd5f 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -1628,6 +1628,11 @@ static void virt_set_memmap(VirtMachineState *vms)
         exit(EXIT_FAILURE);
     }
 
+    if (!vms->highmem &&
+        vms->memmap[VIRT_MEM].base + ms->maxram_size > 4 * GiB) {
+        error_report("highmem=off, but memory crosses the 4GiB limit\n");
+        exit(EXIT_FAILURE);
+    }
     /*
      * We compute the base of the high IO region depending on the
      * amount of initial and device memory. The device memory start/size
@@ -1657,7 +1662,9 @@ static void virt_set_memmap(VirtMachineState *vms)
         vms->memmap[i].size = size;
         base += size;
     }
-    vms->highest_gpa = base - 1;
+    vms->highest_gpa = (vms->highmem ?
+                        base :
+                        vms->memmap[VIRT_MEM].base + ms->maxram_size) - 1;
     if (device_memory_size > 0) {
         ms->device_memory = g_malloc0(sizeof(*ms->device_memory));
         ms->device_memory->base = device_memory_base;
-- 
2.30.2

