[PATCH] x86, aperture: Check for GART before accessing GART registers

Aravind Gopalakrishnan
2015-04-01T20:38:11Z

GART registers are not present in newer processors (Fam15h, Model 10h
and later). So, avoid accesses to GART registers in PCI config
space by returning early in early_gart_iommu_check() and
gart_iommu_hole_init() if GART is not available.

Refactoring the family check used in amd_nb into an inline function
so we can use it here as well as in amd_nb.c

Tested the patch on Fam10h and Fam15h Model 00h-fh and this code
runs fine. On Fam15h Model 60h-6fh and on Fam16h, we bail early
as they don't have GART.

Signed-off-by: Aravind Gopalakrishnan <Aravind.Gopalakrishnan@amd.com>
Reviewed-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>
---
arch/x86/include/asm/amd_nb.h | 11 +++++++++++
arch/x86/kernel/amd_nb.c | 4 +---
arch/x86/kernel/aperture_64.c | 4 ++--
3 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/arch/x86/include/asm/amd_nb.h b/arch/x86/include/asm/amd_nb.h
index aaac3b2..864c8bd 100644
--- a/arch/x86/include/asm/amd_nb.h
+++ b/arch/x86/include/asm/amd_nb.h
@@ -98,11 +98,22 @@ static inline u16 amd_get_node_id(struct pci_dev *pdev)
return 0;
}

+static inline bool amd_gart_present(void)
+{
+ /* GART present only on Fam15h upto model 0fh */
+ if (boot_cpu_data.x86 == 0xf || boot_cpu_data.x86 == 0x10 ||
+ (boot_cpu_data.x86 == 0x15 && boot_cpu_data.x86_model < 0x10))
+ return true;
+
+ return false;
+}
+
#else

#define amd_nb_num(x) 0
#define amd_nb_has_feature(x) false
#define node_to_amd_nb(x) NULL
+#define amd_gart_present(x) false

#endif

diff --git a/arch/x86/kernel/amd_nb.c b/arch/x86/kernel/amd_nb.c
index 5caed1d..29fa475 100644
--- a/arch/x86/kernel/amd_nb.c
+++ b/arch/x86/kernel/amd_nb.c
@@ -89,9 +89,7 @@ int amd_cache_northbridges(void)
next_northbridge(link, amd_nb_link_ids);
}

- /* GART present only on Fam15h upto model 0fh */
- if (boot_cpu_data.x86 == 0xf || boot_cpu_data.x86 == 0x10 ||
- (boot_cpu_data.x86 == 0x15 && boot_cpu_data.x86_model < 0x10))
+ if (amd_gart_present())
amd_northbridges.flags |= AMD_NB_GART;

/*
diff --git a/arch/x86/kernel/aperture_64.c b/arch/x86/kernel/aperture_64.c
index 76164e1..1cb170b 100644
--- a/arch/x86/kernel/aperture_64.c
+++ b/arch/x86/kernel/aperture_64.c
@@ -262,7 +262,7 @@ void __init early_gart_iommu_check(void)
u64 aper_base = 0, last_aper_base = 0;
int aper_enabled = 0, last_aper_enabled = 0, last_valid = 0;

- if (!early_pci_allowed())
+ if (!early_pci_allowed() || !amd_gart_present())
return;

/* This is mostly duplicate of iommu_hole_init */
@@ -356,7 +356,7 @@ int __init gart_iommu_hole_init(void)
int i, node;

if (gart_iommu_aperture_disabled || !fix_aperture ||
- !early_pci_allowed())
+ !early_pci_allowed() || !amd_gart_present())
return -ENODEV;

pr_info("Checking aperture...\n");
--
1.9.1