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authorAravind Gopalakrishnan <Aravind.Gopalakrishnan@amd.com>2015-04-07 16:46:37 -0500
committerIngo Molnar <mingo@kernel.org>2015-05-06 11:15:53 +0200
commit1b4574292e9d2d37b3bb437c9e778fd2bba8e170 (patch)
treea5296a81de9f716fa6bb0b062d4336da47fd7428
parent5198b44374adb3f6143459a03c37f103f8a09548 (diff)
downloadlinux-1b4574292e9d2d37b3bb437c9e778fd2bba8e170.tar.bz2
x86/gart: Check for GART support before accessing GART registers
GART registers are not present in newer AMD processors (Fam15h, Model 10h and later). So, avoid accessing those in PCI config space by returning early in early_gart_iommu_check() and gart_iommu_hole_init() if GART is not available. Current code doesn't break on existing processors but there are some side effects: We get bogus AGP aperture messages which are simply noise on GART-less processors: AGP: Node 0: aperture [bus addr 0x00000000-0x01ffffff] (32MB) AGP: Your BIOS doesn't leave aperture memory hole AGP: Please enable the IOMMU option in the BIOS setup AGP: This costs you 64MB of RAM AGP: Mapping aperture over RAM [mem 0xd4000000-0xd7ffffff] We can avoid calling allocate_aperture() and would not have to wastefully reserve 64MB of RAM with memblock_reserve(). Also, we can avoid having to loop through all PCI buses and devices twice, searching for a non-existent AGP bridge if we bail out early. Refactor the family check used in amd_nb.c into an inline function so we can use it here as well as in amd_nb.c Fix some typos while at it. 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> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com> Cc: Bjorn Helgaas <bhelgaas@google.com> Cc: Borislav Petkov <bp@alien8.de> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Joerg Rodel <joro@8bytes.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1428443197-3834-1-git-send-email-Aravind.Gopalakrishnan@amd.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
-rw-r--r--arch/x86/include/asm/amd_nb.h11
-rw-r--r--arch/x86/kernel/amd_nb.c4
-rw-r--r--arch/x86/kernel/aperture_64.c8
3 files changed, 19 insertions, 4 deletions
diff --git a/arch/x86/include/asm/amd_nb.h b/arch/x86/include/asm/amd_nb.h
index aaac3b2fb746..1a5da2e63aee 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 5caed1dd7ccf..29fa475ec518 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 76164e173a24..6e85f713641d 100644
--- a/arch/x86/kernel/aperture_64.c
+++ b/arch/x86/kernel/aperture_64.c
@@ -262,6 +262,9 @@ 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 (!amd_gart_present())
+ return;
+
if (!early_pci_allowed())
return;
@@ -355,6 +358,9 @@ int __init gart_iommu_hole_init(void)
int fix, slot, valid_agp = 0;
int i, node;
+ if (!amd_gart_present())
+ return -ENODEV;
+
if (gart_iommu_aperture_disabled || !fix_aperture ||
!early_pci_allowed())
return -ENODEV;
@@ -452,7 +458,7 @@ out:
force_iommu ||
valid_agp ||
fallback_aper_force) {
- pr_info("Your BIOS doesn't leave a aperture memory hole\n");
+ pr_info("Your BIOS doesn't leave an aperture memory hole\n");
pr_info("Please enable the IOMMU option in the BIOS setup\n");
pr_info("This costs you %dMB of RAM\n",
32 << fallback_aper_order);