Messages in this thread | | | Date | Wed, 19 Oct 2016 12:32:00 +0100 | From | Matt Fleming <> | Subject | Re: [PATCH] x86/platform/UV: Fix support for EFI_OLD_MEMMAP after BIOS callback updates |
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On Tue, 18 Oct, at 07:47:38AM, Alex Thorlton wrote: > Some time ago, we brought our UV BIOS callback code up to speed with the > new EFI memory mapping scheme, in commit: > > d1be84a232e3 ("x86/uv: Update uv_bios_call() to use efi_call_virt_pointer()") > > By leveraging some changes that I made to a few of the EFI runtime > callback mechanisms, in commit: > > 80e75596079f ("efi: Convert efi_call_virt() to efi_call_virt_pointer()") > > This got everything running smoothly on UV, with the new EFI mapping > code. However, this left one, small loose end, in that EFI_OLD_MEMMAP > (a.k.a. efi=old_map) will no longer work on UV, on kernels that include > the aforementioned changes. > > At the time this was not a major issue (in fact, it still really isn't), > but there's no reason that EFI_OLD_MEMMAP *shouldn't* work on our > systems. This commit adds a check into uv_bios_call, to see if we have > the EFI_OLD_MEMMAP bit set in efi.flags. If it is set, we fall back to > using our old callback method, which uses efi_call directly on the __va > of our function pointer. > > Signed-off-by: Alex Thorlton <athorlton@sgi.com> > Cc: Mike Travis <travis@sgi.com> > Cc: Russ Anderson <rja@sgi.com> > Cc: Dimitri Sivanich <sivanich@sgi.com> > Cc: Thomas Gleixner <tglx@linutronix.de> > Cc: Ingo Molnar <mingo@redhat.com> > Cc: "H. Peter Anvin" <hpa@zytor.com> > Cc: Matt Fleming <matt@codeblueprint.co.uk> > Cc: Masahiro Yamada <yamada.masahiro@socionext.com> > Cc: x86@kernel.org > --- > arch/x86/platform/uv/bios_uv.c | 10 +++++++++- > 1 file changed, 9 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/platform/uv/bios_uv.c b/arch/x86/platform/uv/bios_uv.c > index b4d5e95..12b6e52 100644 > --- a/arch/x86/platform/uv/bios_uv.c > +++ b/arch/x86/platform/uv/bios_uv.c > @@ -40,7 +40,15 @@ s64 uv_bios_call(enum uv_bios_cmd which, u64 a1, u64 a2, u64 a3, u64 a4, u64 a5) > */ > return BIOS_STATUS_UNIMPLEMENTED; > > - ret = efi_call_virt_pointer(tab, function, (u64)which, a1, a2, a3, a4, a5); > + /* > + * If EFI_OLD_MEMMAP is set, we need to fall back to using our old EFI > + * callback method, which uses efi_call directly, with the kernel page tables. > + */ > + if (!test_bit(EFI_OLD_MEMMAP, &efi.flags)) > + ret = efi_call_virt_pointer(tab, function, (u64)which, a1, a2, a3, a4, a5); > + else > + ret = efi_call((void *)__va(tab->function), (u64)which, a1, a2, a3, a4, a5); > + > return ret; > } > EXPORT_SYMBOL_GPL(uv_bios_call);
Could you please invert the conditional? I had to read it 3 times to make sure it was correct given the comment that precedes it. E.g. this is preferable,
if (efi_enabled(EFI_OLD_MEMMAP)) ret = efi_call((void *)__va(tab->function), (u64)which, a1, a2, a3, a4, a5); else ret = efi_call_virt_pointer(tab, function, (u64)which, a1, a2, a3, a4, a5);
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