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OvmfPkg/PlatformInitLib: limit phys-bits to 46. 

Older linux kernels have problems with phys-bits larger than 46,
ubuntu 18.04 (kernel 4.15) has been reported to be affected.

Reduce phys-bits limit from 47 to 46.

Reported-by: Fiona Ebner <f.ebner@proxmox.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
This commit is contained in:
Gerd Hoffmann 2023-06-01 09:57:31 +02:00 committed by mergify[bot]
parent 578a715cfc
commit c1e8537690
1 changed files with 6 additions and 3 deletions
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9
OvmfPkg/Library/PlatformInitLib/MemDetect.c
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@ -646,16 +646,19 @@ PlatformAddressWidthFromCpuid (
)); ));
if (Valid) { if (Valid) {
if (PhysBits > 47) { if (PhysBits > 46) {
/* /*
* Avoid 5-level paging altogether for now, which limits * Avoid 5-level paging altogether for now, which limits
* PhysBits to 48. Also avoid using address bit 48, due to sign * PhysBits to 48. Also avoid using address bit 48, due to sign
* extension we can't identity-map these addresses (and lots of * extension we can't identity-map these addresses (and lots of
* places in edk2 assume we have everything identity-mapped). * places in edk2 assume we have everything identity-mapped).
* So the actual limit is 47. * So the actual limit is 47.
*
* Also some older linux kernels apparently have problems handling
* phys-bits > 46 correctly, so use that as limit.
*/ */
DEBUG ((DEBUG_INFO, "%a: limit PhysBits to 47 (avoid 5-level paging)\n", __func__)); DEBUG ((DEBUG_INFO, "%a: limit PhysBits to 46 (avoid 5-level paging)\n", __func__));
PhysBits = 47; PhysBits = 46;
} }
if (!Page1GSupport && (PhysBits > 40)) { if (!Page1GSupport && (PhysBits > 40)) {