* [PATCH 1/1] OvmfPkg/PlatformInitLib: limit phys-bits to 46.
@ 2023-06-01 7:57 Gerd Hoffmann
2023-06-01 8:13 ` Ard Biesheuvel
0 siblings, 1 reply; 3+ messages in thread
From: Gerd Hoffmann @ 2023-06-01 7:57 UTC (permalink / raw)
To: devel
Cc: Gerd Hoffmann, Jordan Justen, Oliver Steffen, Pawel Polawski,
Ard Biesheuvel, Jiewen Yao, Fiona Ebner
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>
---
OvmfPkg/Library/PlatformInitLib/MemDetect.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/OvmfPkg/Library/PlatformInitLib/MemDetect.c b/OvmfPkg/Library/PlatformInitLib/MemDetect.c
index 1102b00ecbf0..662e7e85bbc5 100644
--- a/OvmfPkg/Library/PlatformInitLib/MemDetect.c
+++ b/OvmfPkg/Library/PlatformInitLib/MemDetect.c
@@ -646,16 +646,19 @@ PlatformAddressWidthFromCpuid (
));
if (Valid) {
- if (PhysBits > 47) {
+ if (PhysBits > 46) {
/*
* Avoid 5-level paging altogether for now, which limits
* PhysBits to 48. Also avoid using address bit 48, due to sign
* extension we can't identity-map these addresses (and lots of
* places in edk2 assume we have everything identity-mapped).
* 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__));
- PhysBits = 47;
+ DEBUG ((DEBUG_INFO, "%a: limit PhysBits to 46 (avoid 5-level paging)\n", __func__));
+ PhysBits = 46;
}
if (!Page1GSupport && (PhysBits > 40)) {
--
2.40.1
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH 1/1] OvmfPkg/PlatformInitLib: limit phys-bits to 46.
2023-06-01 7:57 [PATCH 1/1] OvmfPkg/PlatformInitLib: limit phys-bits to 46 Gerd Hoffmann
@ 2023-06-01 8:13 ` Ard Biesheuvel
2023-06-01 9:07 ` Ard Biesheuvel
0 siblings, 1 reply; 3+ messages in thread
From: Ard Biesheuvel @ 2023-06-01 8:13 UTC (permalink / raw)
To: Gerd Hoffmann
Cc: devel, Jordan Justen, Oliver Steffen, Pawel Polawski,
Ard Biesheuvel, Jiewen Yao, Fiona Ebner
On Thu, 1 Jun 2023 at 09:57, Gerd Hoffmann <kraxel@redhat.com> wrote:
>
> 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>
Thanks I'll queue this up
> ---
> OvmfPkg/Library/PlatformInitLib/MemDetect.c | 9 ++++++---
> 1 file changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/OvmfPkg/Library/PlatformInitLib/MemDetect.c b/OvmfPkg/Library/PlatformInitLib/MemDetect.c
> index 1102b00ecbf0..662e7e85bbc5 100644
> --- a/OvmfPkg/Library/PlatformInitLib/MemDetect.c
> +++ b/OvmfPkg/Library/PlatformInitLib/MemDetect.c
> @@ -646,16 +646,19 @@ PlatformAddressWidthFromCpuid (
> ));
>
> if (Valid) {
> - if (PhysBits > 47) {
> + if (PhysBits > 46) {
> /*
> * Avoid 5-level paging altogether for now, which limits
> * PhysBits to 48. Also avoid using address bit 48, due to sign
> * extension we can't identity-map these addresses (and lots of
> * places in edk2 assume we have everything identity-mapped).
> * 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__));
> - PhysBits = 47;
> + DEBUG ((DEBUG_INFO, "%a: limit PhysBits to 46 (avoid 5-level paging)\n", __func__));
> + PhysBits = 46;
> }
>
> if (!Page1GSupport && (PhysBits > 40)) {
> --
> 2.40.1
>
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH 1/1] OvmfPkg/PlatformInitLib: limit phys-bits to 46.
2023-06-01 8:13 ` Ard Biesheuvel
@ 2023-06-01 9:07 ` Ard Biesheuvel
0 siblings, 0 replies; 3+ messages in thread
From: Ard Biesheuvel @ 2023-06-01 9:07 UTC (permalink / raw)
To: Gerd Hoffmann
Cc: devel, Jordan Justen, Oliver Steffen, Pawel Polawski,
Ard Biesheuvel, Jiewen Yao, Fiona Ebner
On Thu, 1 Jun 2023 at 10:13, Ard Biesheuvel <ardb@kernel.org> wrote:
>
> On Thu, 1 Jun 2023 at 09:57, Gerd Hoffmann <kraxel@redhat.com> wrote:
> >
> > 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>
>
> Thanks I'll queue this up
>
Merged as #4461
> > ---
> > OvmfPkg/Library/PlatformInitLib/MemDetect.c | 9 ++++++---
> > 1 file changed, 6 insertions(+), 3 deletions(-)
> >
> > diff --git a/OvmfPkg/Library/PlatformInitLib/MemDetect.c b/OvmfPkg/Library/PlatformInitLib/MemDetect.c
> > index 1102b00ecbf0..662e7e85bbc5 100644
> > --- a/OvmfPkg/Library/PlatformInitLib/MemDetect.c
> > +++ b/OvmfPkg/Library/PlatformInitLib/MemDetect.c
> > @@ -646,16 +646,19 @@ PlatformAddressWidthFromCpuid (
> > ));
> >
> > if (Valid) {
> > - if (PhysBits > 47) {
> > + if (PhysBits > 46) {
> > /*
> > * Avoid 5-level paging altogether for now, which limits
> > * PhysBits to 48. Also avoid using address bit 48, due to sign
> > * extension we can't identity-map these addresses (and lots of
> > * places in edk2 assume we have everything identity-mapped).
> > * 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__));
> > - PhysBits = 47;
> > + DEBUG ((DEBUG_INFO, "%a: limit PhysBits to 46 (avoid 5-level paging)\n", __func__));
> > + PhysBits = 46;
> > }
> >
> > if (!Page1GSupport && (PhysBits > 40)) {
> > --
> > 2.40.1
> >
^ permalink raw reply [flat|nested] 3+ messages in thread
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2023-06-01 7:57 [PATCH 1/1] OvmfPkg/PlatformInitLib: limit phys-bits to 46 Gerd Hoffmann
2023-06-01 8:13 ` Ard Biesheuvel
2023-06-01 9:07 ` Ard Biesheuvel
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