Commit d5052a7130a6 ("x86/efi: Unmap EFI boot services code/data regions
from efi_pgd") forgets to take two EFI modes into consideration namely
EFI_OLD_MEMMAP and EFI_MIXED_MODE.
EFI_OLD_MEMMAP is a legacy way of mapping EFI regions into swapper_pg_dir
using ioremap() and init_memory_mapping(). This feature can be enabled by
passing "efi=old_map" as kernel command line argument. But,
efi_unmap_pages() unmaps EFI boot services code/data regions *only* from
efi_pgd and hence cannot be used for unmapping EFI boot services code/data
regions from swapper_pg_dir.
Introduce a temporary fix to not unmap EFI boot services code/data regions
when EFI_OLD_MEMMAP is enabled while working on a real fix.
EFI_MIXED_MODE is another feature where a 64-bit kernel runs on a
64-bit platform crippled by a 32-bit firmware. To support EFI_MIXED_MODE,
all RAM (i.e. namely EFI regions like EFI_CONVENTIONAL_MEMORY,
EFI_LOADER_<CODE/DATA>, EFI_BOOT_SERVICES_<CODE/DATA> and
EFI_RUNTIME_CODE/DATA regions) is mapped into efi_pgd all the time to
facilitate EFI runtime calls access it's arguments in 1:1 mode. Hence,
don't unmap EFI boot services code/data regions when booted in mixed mode.
Signed-off-by: Sai Praneeth Prakhya <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Bhupesh Sharma <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Ard Biesheuvel <[email protected]>
---
arch/x86/platform/efi/quirks.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff --git a/arch/x86/platform/efi/quirks.c b/arch/x86/platform/efi/quirks.c
index 09e811b9da26..9c34230aaeae 100644
--- a/arch/x86/platform/efi/quirks.c
+++ b/arch/x86/platform/efi/quirks.c
@@ -380,6 +380,22 @@ static void __init efi_unmap_pages(efi_memory_desc_t *md)
u64 pa = md->phys_addr;
u64 va = md->virt_addr;
+ /*
+ * To Do: Remove this check after adding functionality to unmap EFI boot
+ * services code/data regions from direct mapping area because
+ * "efi=old_map" maps EFI regions in swapper_pg_dir.
+ */
+ if (efi_enabled(EFI_OLD_MEMMAP))
+ return;
+
+ /*
+ * EFI mixed mode has all RAM mapped to access arguments while making
+ * EFI runtime calls, hence don't unmap EFI boot services code/data
+ * regions.
+ */
+ if (!efi_is_native() && IS_ENABLED(CONFIG_EFI_MIXED))
+ return;
+
if (kernel_unmap_pages_in_pgd(pgd, pa, md->num_pages))
pr_err("Failed to unmap 1:1 mapping for 0x%llx\n", pa);
--
2.19.1
On Sat, 22 Dec 2018 at 11:54, Ingo Molnar <[email protected]> wrote:
>
>
> * Sai Praneeth Prakhya <[email protected]> wrote:
>
> > Commit d5052a7130a6 ("x86/efi: Unmap EFI boot services code/data regions
> > from efi_pgd") forgets to take two EFI modes into consideration namely
> > EFI_OLD_MEMMAP and EFI_MIXED_MODE.
>
> So the commit sha1 ended up being this one in tip:efi/core:
>
> 08cfb38f3ef4: x86/efi: Unmap EFI boot services code/data regions from efi_pgd
>
> > EFI_OLD_MEMMAP is a legacy way of mapping EFI regions into swapper_pg_dir
> > using ioremap() and init_memory_mapping(). This feature can be enabled by
> > passing "efi=old_map" as kernel command line argument. But,
> > efi_unmap_pages() unmaps EFI boot services code/data regions *only* from
> > efi_pgd and hence cannot be used for unmapping EFI boot services code/data
> > regions from swapper_pg_dir.
> >
> > Introduce a temporary fix to not unmap EFI boot services code/data regions
> > when EFI_OLD_MEMMAP is enabled while working on a real fix.
> >
> > EFI_MIXED_MODE is another feature where a 64-bit kernel runs on a
> > 64-bit platform crippled by a 32-bit firmware. To support EFI_MIXED_MODE,
> > all RAM (i.e. namely EFI regions like EFI_CONVENTIONAL_MEMORY,
> > EFI_LOADER_<CODE/DATA>, EFI_BOOT_SERVICES_<CODE/DATA> and
> > EFI_RUNTIME_CODE/DATA regions) is mapped into efi_pgd all the time to
> > facilitate EFI runtime calls access it's arguments in 1:1 mode. Hence,
> > don't unmap EFI boot services code/data regions when booted in mixed mode.
> >
> > Signed-off-by: Sai Praneeth Prakhya <[email protected]>
> > Cc: Borislav Petkov <[email protected]>
> > Cc: Ingo Molnar <[email protected]>
> > Cc: Andy Lutomirski <[email protected]>
> > Cc: Dave Hansen <[email protected]>
> > Cc: Bhupesh Sharma <[email protected]>
> > Cc: Peter Zijlstra <[email protected]>
> > Cc: Thomas Gleixner <[email protected]>
> > Cc: Ard Biesheuvel <[email protected]>
> > ---
> > arch/x86/platform/efi/quirks.c | 16 ++++++++++++++++
> > 1 file changed, 16 insertions(+)
> >
> > diff --git a/arch/x86/platform/efi/quirks.c b/arch/x86/platform/efi/quirks.c
> > index 09e811b9da26..9c34230aaeae 100644
> > --- a/arch/x86/platform/efi/quirks.c
> > +++ b/arch/x86/platform/efi/quirks.c
> > @@ -380,6 +380,22 @@ static void __init efi_unmap_pages(efi_memory_desc_t *md)
> > u64 pa = md->phys_addr;
> > u64 va = md->virt_addr;
> >
> > + /*
> > + * To Do: Remove this check after adding functionality to unmap EFI boot
> > + * services code/data regions from direct mapping area because
> > + * "efi=old_map" maps EFI regions in swapper_pg_dir.
> > + */
> > + if (efi_enabled(EFI_OLD_MEMMAP))
> > + return;
> > +
> > + /*
> > + * EFI mixed mode has all RAM mapped to access arguments while making
> > + * EFI runtime calls, hence don't unmap EFI boot services code/data
> > + * regions.
> > + */
> > + if (!efi_is_native() && IS_ENABLED(CONFIG_EFI_MIXED))
AFAIK efi_is_native() can only return false is CONFIG_EFI_MIXED is
set, so this expression can be simplified.
> > + return;
>
> I suppose old_mmap and mixed mode stopped working altogether after the
> unmapping changes? What are the symptoms, instant reboots, crasher, or
> some more benign behavior like non-working runtime EFI functionality?
>
> If Ard acks this I'll apply it immediately, as these bugs look like
> show-stoppers for merging the EFI tree into v4.21.
>
Acked-by: Ard Biesheuvel <[email protected]>
with the sidenote that I won't be able to test this myself until
monday at the earliest.
* Sai Praneeth Prakhya <[email protected]> wrote:
> Commit d5052a7130a6 ("x86/efi: Unmap EFI boot services code/data regions
> from efi_pgd") forgets to take two EFI modes into consideration namely
> EFI_OLD_MEMMAP and EFI_MIXED_MODE.
So the commit sha1 ended up being this one in tip:efi/core:
08cfb38f3ef4: x86/efi: Unmap EFI boot services code/data regions from efi_pgd
> EFI_OLD_MEMMAP is a legacy way of mapping EFI regions into swapper_pg_dir
> using ioremap() and init_memory_mapping(). This feature can be enabled by
> passing "efi=old_map" as kernel command line argument. But,
> efi_unmap_pages() unmaps EFI boot services code/data regions *only* from
> efi_pgd and hence cannot be used for unmapping EFI boot services code/data
> regions from swapper_pg_dir.
>
> Introduce a temporary fix to not unmap EFI boot services code/data regions
> when EFI_OLD_MEMMAP is enabled while working on a real fix.
>
> EFI_MIXED_MODE is another feature where a 64-bit kernel runs on a
> 64-bit platform crippled by a 32-bit firmware. To support EFI_MIXED_MODE,
> all RAM (i.e. namely EFI regions like EFI_CONVENTIONAL_MEMORY,
> EFI_LOADER_<CODE/DATA>, EFI_BOOT_SERVICES_<CODE/DATA> and
> EFI_RUNTIME_CODE/DATA regions) is mapped into efi_pgd all the time to
> facilitate EFI runtime calls access it's arguments in 1:1 mode. Hence,
> don't unmap EFI boot services code/data regions when booted in mixed mode.
>
> Signed-off-by: Sai Praneeth Prakhya <[email protected]>
> Cc: Borislav Petkov <[email protected]>
> Cc: Ingo Molnar <[email protected]>
> Cc: Andy Lutomirski <[email protected]>
> Cc: Dave Hansen <[email protected]>
> Cc: Bhupesh Sharma <[email protected]>
> Cc: Peter Zijlstra <[email protected]>
> Cc: Thomas Gleixner <[email protected]>
> Cc: Ard Biesheuvel <[email protected]>
> ---
> arch/x86/platform/efi/quirks.c | 16 ++++++++++++++++
> 1 file changed, 16 insertions(+)
>
> diff --git a/arch/x86/platform/efi/quirks.c b/arch/x86/platform/efi/quirks.c
> index 09e811b9da26..9c34230aaeae 100644
> --- a/arch/x86/platform/efi/quirks.c
> +++ b/arch/x86/platform/efi/quirks.c
> @@ -380,6 +380,22 @@ static void __init efi_unmap_pages(efi_memory_desc_t *md)
> u64 pa = md->phys_addr;
> u64 va = md->virt_addr;
>
> + /*
> + * To Do: Remove this check after adding functionality to unmap EFI boot
> + * services code/data regions from direct mapping area because
> + * "efi=old_map" maps EFI regions in swapper_pg_dir.
> + */
> + if (efi_enabled(EFI_OLD_MEMMAP))
> + return;
> +
> + /*
> + * EFI mixed mode has all RAM mapped to access arguments while making
> + * EFI runtime calls, hence don't unmap EFI boot services code/data
> + * regions.
> + */
> + if (!efi_is_native() && IS_ENABLED(CONFIG_EFI_MIXED))
> + return;
I suppose old_mmap and mixed mode stopped working altogether after the
unmapping changes? What are the symptoms, instant reboots, crasher, or
some more benign behavior like non-working runtime EFI functionality?
If Ard acks this I'll apply it immediately, as these bugs look like
show-stoppers for merging the EFI tree into v4.21.
Thanks,
Ingo
>
> * Sai Praneeth Prakhya <[email protected]> wrote:
>
> > Commit d5052a7130a6 ("x86/efi: Unmap EFI boot services code/data
> > regions from efi_pgd") forgets to take two EFI modes into
> > consideration namely EFI_OLD_MEMMAP and EFI_MIXED_MODE.
>
> So the commit sha1 ended up being this one in tip:efi/core:
>
> 08cfb38f3ef4: x86/efi: Unmap EFI boot services code/data regions from
> efi_pgd
Ya.. sorry! I took the sha1 from efi tree.
>
> > EFI_OLD_MEMMAP is a legacy way of mapping EFI regions into
> > swapper_pg_dir using ioremap() and init_memory_mapping(). This feature
> > can be enabled by passing "efi=old_map" as kernel command line
> > argument. But,
> > efi_unmap_pages() unmaps EFI boot services code/data regions *only*
> > from efi_pgd and hence cannot be used for unmapping EFI boot services
> > code/data regions from swapper_pg_dir.
[.........]
> > + /*
> > + * EFI mixed mode has all RAM mapped to access arguments while
> making
> > + * EFI runtime calls, hence don't unmap EFI boot services code/data
> > + * regions.
> > + */
> > + if (!efi_is_native() && IS_ENABLED(CONFIG_EFI_MIXED))
> > + return;
>
> I suppose old_mmap and mixed mode stopped working altogether after the
> unmapping changes?
Yes.. that's true.
> What are the symptoms, instant reboots, crasher, or some
> more benign behavior like non-working runtime EFI functionality?
I noticed a kernel panic due to page fault.
AFAIK, it happens because efi_pgd is not defined for old_map and mixed mode.
Hence efi_unmap_pages() which calls __change_page_attr() unmaps mappings
from swapper_pg_dir (please note that this my theory but I haven't checked if
this is really true).
>
> If Ard acks this I'll apply it immediately, as these bugs look like show-stoppers for
> merging the EFI tree into v4.21.
>
> Thanks,
>
> Ingo
Commit-ID: 1debf0958fa27b7c469dbf22754929ec59a7c0e7
Gitweb: https://git.kernel.org/tip/1debf0958fa27b7c469dbf22754929ec59a7c0e7
Author: Sai Praneeth Prakhya <[email protected]>
AuthorDate: Fri, 21 Dec 2018 18:22:34 -0800
Committer: Ingo Molnar <[email protected]>
CommitDate: Sat, 22 Dec 2018 20:58:30 +0100
x86/efi: Don't unmap EFI boot services code/data regions for EFI_OLD_MEMMAP and EFI_MIXED_MODE
The following commit:
d5052a7130a6 ("x86/efi: Unmap EFI boot services code/data regions from efi_pgd")
forgets to take two EFI modes into consideration, namely EFI_OLD_MEMMAP and
EFI_MIXED_MODE:
- EFI_OLD_MEMMAP is a legacy way of mapping EFI regions into swapper_pg_dir
using ioremap() and init_memory_mapping(). This feature can be enabled by
passing "efi=old_map" as kernel command line argument. But,
efi_unmap_pages() unmaps EFI boot services code/data regions *only* from
efi_pgd and hence cannot be used for unmapping EFI boot services code/data
regions from swapper_pg_dir.
Introduce a temporary fix to not unmap EFI boot services code/data regions
when EFI_OLD_MEMMAP is enabled while working on a real fix.
- EFI_MIXED_MODE is another feature where a 64-bit kernel runs on a
64-bit platform crippled by a 32-bit firmware. To support EFI_MIXED_MODE,
all RAM (i.e. namely EFI regions like EFI_CONVENTIONAL_MEMORY,
EFI_LOADER_<CODE/DATA>, EFI_BOOT_SERVICES_<CODE/DATA> and
EFI_RUNTIME_CODE/DATA regions) is mapped into efi_pgd all the time to
facilitate EFI runtime calls access it's arguments in 1:1 mode.
Hence, don't unmap EFI boot services code/data regions when booted in mixed mode.
Signed-off-by: Sai Praneeth Prakhya <[email protected]>
Acked-by: Ard Biesheuvel <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Bhupesh Sharma <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Rik van Riel <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
---
arch/x86/platform/efi/quirks.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff --git a/arch/x86/platform/efi/quirks.c b/arch/x86/platform/efi/quirks.c
index 09e811b9da26..17456a1d3f04 100644
--- a/arch/x86/platform/efi/quirks.c
+++ b/arch/x86/platform/efi/quirks.c
@@ -380,6 +380,22 @@ static void __init efi_unmap_pages(efi_memory_desc_t *md)
u64 pa = md->phys_addr;
u64 va = md->virt_addr;
+ /*
+ * To Do: Remove this check after adding functionality to unmap EFI boot
+ * services code/data regions from direct mapping area because
+ * "efi=old_map" maps EFI regions in swapper_pg_dir.
+ */
+ if (efi_enabled(EFI_OLD_MEMMAP))
+ return;
+
+ /*
+ * EFI mixed mode has all RAM mapped to access arguments while making
+ * EFI runtime calls, hence don't unmap EFI boot services code/data
+ * regions.
+ */
+ if (!efi_is_native())
+ return;
+
if (kernel_unmap_pages_in_pgd(pgd, pa, md->num_pages))
pr_err("Failed to unmap 1:1 mapping for 0x%llx\n", pa);
On Sat, 22 Dec 2018 at 12:04, Ard Biesheuvel <[email protected]> wrote:
>
> On Sat, 22 Dec 2018 at 11:54, Ingo Molnar <[email protected]> wrote:
> >
> >
> > * Sai Praneeth Prakhya <[email protected]> wrote:
> >
> > > Commit d5052a7130a6 ("x86/efi: Unmap EFI boot services code/data regions
> > > from efi_pgd") forgets to take two EFI modes into consideration namely
> > > EFI_OLD_MEMMAP and EFI_MIXED_MODE.
> >
> > So the commit sha1 ended up being this one in tip:efi/core:
> >
> > 08cfb38f3ef4: x86/efi: Unmap EFI boot services code/data regions from efi_pgd
> >
> > > EFI_OLD_MEMMAP is a legacy way of mapping EFI regions into swapper_pg_dir
> > > using ioremap() and init_memory_mapping(). This feature can be enabled by
> > > passing "efi=old_map" as kernel command line argument. But,
> > > efi_unmap_pages() unmaps EFI boot services code/data regions *only* from
> > > efi_pgd and hence cannot be used for unmapping EFI boot services code/data
> > > regions from swapper_pg_dir.
> > >
> > > Introduce a temporary fix to not unmap EFI boot services code/data regions
> > > when EFI_OLD_MEMMAP is enabled while working on a real fix.
> > >
> > > EFI_MIXED_MODE is another feature where a 64-bit kernel runs on a
> > > 64-bit platform crippled by a 32-bit firmware. To support EFI_MIXED_MODE,
> > > all RAM (i.e. namely EFI regions like EFI_CONVENTIONAL_MEMORY,
> > > EFI_LOADER_<CODE/DATA>, EFI_BOOT_SERVICES_<CODE/DATA> and
> > > EFI_RUNTIME_CODE/DATA regions) is mapped into efi_pgd all the time to
> > > facilitate EFI runtime calls access it's arguments in 1:1 mode. Hence,
> > > don't unmap EFI boot services code/data regions when booted in mixed mode.
> > >
> > > Signed-off-by: Sai Praneeth Prakhya <[email protected]>
> > > Cc: Borislav Petkov <[email protected]>
> > > Cc: Ingo Molnar <[email protected]>
> > > Cc: Andy Lutomirski <[email protected]>
> > > Cc: Dave Hansen <[email protected]>
> > > Cc: Bhupesh Sharma <[email protected]>
> > > Cc: Peter Zijlstra <[email protected]>
> > > Cc: Thomas Gleixner <[email protected]>
> > > Cc: Ard Biesheuvel <[email protected]>
> > > ---
> > > arch/x86/platform/efi/quirks.c | 16 ++++++++++++++++
> > > 1 file changed, 16 insertions(+)
> > >
> > > diff --git a/arch/x86/platform/efi/quirks.c b/arch/x86/platform/efi/quirks.c
> > > index 09e811b9da26..9c34230aaeae 100644
> > > --- a/arch/x86/platform/efi/quirks.c
> > > +++ b/arch/x86/platform/efi/quirks.c
> > > @@ -380,6 +380,22 @@ static void __init efi_unmap_pages(efi_memory_desc_t *md)
> > > u64 pa = md->phys_addr;
> > > u64 va = md->virt_addr;
> > >
> > > + /*
> > > + * To Do: Remove this check after adding functionality to unmap EFI boot
> > > + * services code/data regions from direct mapping area because
> > > + * "efi=old_map" maps EFI regions in swapper_pg_dir.
> > > + */
> > > + if (efi_enabled(EFI_OLD_MEMMAP))
> > > + return;
> > > +
> > > + /*
> > > + * EFI mixed mode has all RAM mapped to access arguments while making
> > > + * EFI runtime calls, hence don't unmap EFI boot services code/data
> > > + * regions.
> > > + */
> > > + if (!efi_is_native() && IS_ENABLED(CONFIG_EFI_MIXED))
>
> AFAIK efi_is_native() can only return false is CONFIG_EFI_MIXED is
> set, so this expression can be simplified.
>
> > > + return;
> >
> > I suppose old_mmap and mixed mode stopped working altogether after the
> > unmapping changes? What are the symptoms, instant reboots, crasher, or
> > some more benign behavior like non-working runtime EFI functionality?
> >
> > If Ard acks this I'll apply it immediately, as these bugs look like
> > show-stoppers for merging the EFI tree into v4.21.
> >
>
> Acked-by: Ard Biesheuvel <[email protected]>
>
> with the sidenote that I won't be able to test this myself until
> monday at the earliest.
OK, so I have tested both efi=old_map and mixed mode before and after
applying this patch, using QEMU/KVM with 64-bit and 32-bit builds of
OVMF [respectively]
efi=old_map is indeed broken before and needs this patch.
Mixed mode works just fine both before and after applying the patch,
but I suggest we keep this patch as-is and address mixed mode later if
needed (I spotted a couple of things in the boot log that may need
some attention but I'm not sure if the issue is in Linux or in OVMF)
* Prakhya, Sai Praneeth <[email protected]> wrote:
> > > > + /*
> > > > + * To Do: Remove this check after adding functionality to unmap EFI
> > boot
> > > > + * services code/data regions from direct mapping area because
> > > > + * "efi=old_map" maps EFI regions in swapper_pg_dir.
> > > > + */
> > > > + if (efi_enabled(EFI_OLD_MEMMAP))
> > > > + return;
> > > > +
> > > > + /*
> > > > + * EFI mixed mode has all RAM mapped to access arguments while
> > making
> > > > + * EFI runtime calls, hence don't unmap EFI boot services code/data
> > > > + * regions.
> > > > + */
> > > > + if (!efi_is_native() && IS_ENABLED(CONFIG_EFI_MIXED))
> >
> > AFAIK efi_is_native() can only return false is CONFIG_EFI_MIXED is set, so this
> > expression can be simplified.
>
> Makes sense.
> efi_is_native() returns true for 32-bit machines running 32-bit firmware.
Forgot to mention that I performed this simplification in the commit I
applied:
+ /*
+ * To Do: Remove this check after adding functionality to unmap EFI boot
+ * services code/data regions from direct mapping area because
+ * "efi=old_map" maps EFI regions in swapper_pg_dir.
+ */
+ if (efi_enabled(EFI_OLD_MEMMAP))
+ return;
+
+ /*
+ * EFI mixed mode has all RAM mapped to access arguments while making
+ * EFI runtime calls, hence don't unmap EFI boot services code/data
+ * regions.
+ */
+ if (!efi_is_native())
+ return;
Thanks,
Ingo
> > Acked-by: Ard Biesheuvel <[email protected]>
> >
> > with the sidenote that I won't be able to test this myself until
> > monday at the earliest.
>
> OK, so I have tested both efi=old_map and mixed mode before and after
> applying this patch, using QEMU/KVM with 64-bit and 32-bit builds of OVMF
> [respectively]
>
> efi=old_map is indeed broken before and needs this patch.
>
> Mixed mode works just fine both before and after applying the patch, but I
> suggest we keep this patch as-is and address mixed mode later if needed (I
> spotted a couple of things in the boot log that may need some attention but I'm
> not sure if the issue is in Linux or in OVMF)
Thanks for testing this Ard.
For testing Mixed mode, I have used QEMU/KVM with 64-bit and 32-bit OVMF
and mixed mode is broken for me without this patch.
I am using an older OVMF build and probably that might be the reason for us seeing
different behaviors. Also, kernel config file might have some role to play.. I guess.
Regards,
Sai