[PATCH] x86/platform/UV: Bring back the call to map_low_mmrs in uv_system_init

[Alex Thorlton]

A while back, commit d394f2d9d8e1 ("x86/platform/UV: Remove EFI memmap
quirk for UV2+") changed uv_system_init to only call map_low_mmrs on
older UV1 hardware, which requires EFI_OLD_MEMMAP to be set in order to
boot.  The recent changes to the EFI memory mapping code in commit
d2f7cbe7b26a ("x86/efi: Runtime services virtual mapping") exposed some
issues with the fact that we were relying on the EFI memory mapping
mechanisms to map in our MMRs for us, after commit d394f2d9d8e1.

Rather than revert the entire commit and go back to forcing
EFI_OLD_MEMMAP on all UVs, we're going to add the call to map_low_mmrs
back into uv_system_init, and then fix up our EFI runtime calls to use
the appropriate page table.

For now, UV2+ will still need efi=old_map to boot, but there will be
other changes soon that should eliminate the need for this.

Signed-off-by: Alex Thorlton <athorlton@xxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Matt Fleming <matt@xxxxxxxxxxxxxxxxxxx>
Cc: Adam Buchbinder <adam.buchbinder@xxxxxxxxx>
Cc: Len Brown <len.brown@xxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxx>
Cc: Russ Anderson <rja@xxxxxxx>
Cc: Dimitri Sivanich <sivanich@xxxxxxx>
Cc: x86@xxxxxxxxxx
---
 arch/x86/kernel/apic/x2apic_uv_x.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/arch/x86/kernel/apic/x2apic_uv_x.c b/arch/x86/kernel/apic/x2apic_uv_x.c
index 8f4942e..d7ce96a 100644
--- a/arch/x86/kernel/apic/x2apic_uv_x.c
+++ b/arch/x86/kernel/apic/x2apic_uv_x.c
@@ -891,9 +891,7 @@ void __init uv_system_init(void)
 	}
 	pr_info("UV: Found %s hub\n", hub);
 
-	/* We now only need to map the MMRs on UV1 */
-	if (is_uv1_hub())
-		map_low_mmrs();
+	map_low_mmrs();
 
 	m_n_config.v = uv_read_local_mmr(UVH_RH_GAM_CONFIG_MMR );
 	m_val = m_n_config.s.m_skt;
-- 
1.8.5.6