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Date: Fri, 27 Nov 2009 16:29:32 +0900
From: FUJITA Tomonori <fujita.tomonori@....ntt.co.jp>
To: yinghai@...nel.org
Cc: fujita.tomonori@....ntt.co.jp, mingo@...e.hu,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH -tip] x86: fix iommu=soft boot option
On Wed, 25 Nov 2009 14:33:27 -0800
Yinghai Lu <yinghai@...nel.org> wrote:
> in aperture_64.c::gart_iommu_hole_init()
> printk(KERN_INFO "Checking aperture...\n");
>
> if (!fallback_aper_force)
> agp_aper_base = search_agp_bridge(&agp_aper_order, &valid_agp);
>
> fix = 0;
> node = 0;
> for (i = 0; i < ARRAY_SIZE(bus_dev_ranges); i++) {
> int bus;
> int dev_base, dev_limit;
>
> bus = bus_dev_ranges[i].bus;
> dev_base = bus_dev_ranges[i].dev_base;
> dev_limit = bus_dev_ranges[i].dev_limit;
>
> for (slot = dev_base; slot < dev_limit; slot++) {
>
> if (!early_is_k8_nb(read_pci_config(bus, slot, 3, 0x00)))
> continue;
>
> iommu_detected = 1;
> gart_iommu_aperture = 1;
>
> aper_order = (read_pci_config(bus, slot, 3, AMD64_GARTAPERTURECTL) >> 1) & 7;
> aper_size = (32 * 1024 * 1024) << aper_order;
> aper_base = read_pci_config(bus, slot, 3, AMD64_GARTAPERTUREBASE) & 0x7fff;
> aper_base <<= 25;
>
> printk(KERN_INFO "Node %d: aperture @ %Lx size %u MB\n",
> node, aper_base, aper_size >> 20);
> node++;
>
> if (!aperture_valid(aper_base, aper_size, 64<<20)) {
> if (valid_agp && agp_aper_base &&
> agp_aper_base == aper_base &&
> agp_aper_order == aper_order) {
> /* the same between two setting from NB and agp */
> if (!no_iommu &&
> max_pfn > MAX_DMA32_PFN &&
> !printed_gart_size_msg) {
> printk(KERN_ERR "you are using iommu with agp, but GART size is less than 64M\n");
> printk(KERN_ERR "please increase GART size in your BIOS setup\n");
> printk(KERN_ERR "if BIOS doesn't have that option, contact your HW vendor!\n");
> printed_gart_size_msg = 1;
> }
> } else {
> POINT A:
> fix = 1;
> goto out;
> }
> }
>
> if ((last_aper_order && aper_order != last_aper_order) ||
> (last_aper_base && aper_base != last_aper_base)) {
> fix = 1;
> goto out;
> }
> last_aper_order = aper_order;
> last_aper_base = aper_base;
> }
> }
>
> out:
> if (!fix && !fallback_aper_force) {
> if (last_aper_base) {
> unsigned long n = (32 * 1024 * 1024) << last_aper_order;
>
> insert_aperture_resource((u32)last_aper_base, n);
> }
> return;
> }
>
> if (!fallback_aper_force) {
> aper_alloc = agp_aper_base;
> aper_order = agp_aper_order;
> }
>
> if (aper_alloc) {
> /* Got the aperture from the AGP bridge */
> } else if (swiotlb && !valid_agp) {
> POINT: B
> /* Do nothing */
> } else if ((!no_iommu && max_pfn > MAX_DMA32_PFN) ||
> force_iommu ||
> valid_agp ||
> fallback_aper_force) {
> POINT: C
> printk(KERN_INFO
> "Your BIOS doesn't leave a aperture memory hole\n");
> printk(KERN_INFO
> "Please enable the IOMMU option in the BIOS setup\n");
> printk(KERN_INFO
> "This costs you %d MB of RAM\n",
> 32 << fallback_aper_order);
>
> aper_order = fallback_aper_order;
> aper_alloc = allocate_aperture();
> if (!aper_alloc) {
> /*
> * Could disable AGP and IOMMU here, but it's
> * probably not worth it. But the later users
> * cannot deal with bad apertures and turning
> * on the aperture over memory causes very
> * strange problems, so it's better to panic
> * early.
> */
> panic("Not enough memory for aperture");
> }
> } else {
> return;
> }
>
> POINT X:
>
> /* Fix up the north bridges */
> for (i = 0; i < ARRAY_SIZE(bus_dev_ranges); i++) {
> int bus;
> int dev_base, dev_limit;
>
> bus = bus_dev_ranges[i].bus;
> dev_base = bus_dev_ranges[i].dev_base;
> dev_limit = bus_dev_ranges[i].dev_limit;
> for (slot = dev_base; slot < dev_limit; slot++) {
> if (!early_is_k8_nb(read_pci_config(bus, slot, 3, 0x00)))
> continue;
>
> /* Don't enable translation yet. That is done later.
> Assume this BIOS didn't initialise the GART so
> just overwrite all previous bits */
> write_pci_config(bus, slot, 3, AMD64_GARTAPERTURECTL, aper_order << 1);
> write_pci_config(bus, slot, 3, AMD64_GARTAPERTUREBASE, aper_alloc >> 25);
> }
> }
>
> when AMD64 mem > 4g, no AGP, BIOS set all gart iommu on all nodes size to 32M, and enable bit are set.
I have such machine (with sane BIOS).
But if BIOS is broken, early_gart_iommu_check() disables GART_EN bit
(bits 0)?
> 1. iommu=soft, will go through POINT A and POINT B
Not always. if aperture_valid() is true, it doesn't go POINT A. My
GART machine doesn't go.
> 2. no "iommu=soft", will go through POINT A and POINT C
As I said, it's not true about POINT A.
> and all will reach POINT X to make sure ENABLE bit is not set.
POINT X doesn't look make sure ENABLE bit is not set. It just fixes up
(sets) the address and its size.
And with 2.6.31, if I use iommu=soft, my GART machine uses swiotlb but
it still keeps GART_EN bit enabled.
So for what does 'iommu=soft' go to POINT B and POINT X? That is, why
we can't skip them with 'iommu=soft'?
> please check
>
> [PATCH] x86: fix gart iommu using for amd 64 bit system -v3
>
> after
> |commit 75f1cdf1dda92cae037ec848ae63690d91913eac
> |Author: FUJITA Tomonori <fujita.tomonori@....ntt.co.jp>
> |Date: Tue Nov 10 19:46:20 2009 +0900
> |
> | x86: Handle HW IOMMU initialization failure gracefully
> |
> | If HW IOMMU initialization fails (Intel VT-d often does this,
> | typically due to BIOS bugs), we fall back to nommu. It doesn't
> | work for the majority since nowadays we have more than 4GB
> | memory so we must use swiotlb instead of nommu.
> ...
>
> amd 64 systems that
> 1. do not have AGP
> 2. do not have IOMMU
> 3. mem > 4g
> 4. BIOS do not allocate correct gart in NB.
> will leave them to use SWIOTLB forcely.
What should such system use in this case?
> also in pci_iommu_alloc()
> pci_swiotlb_init is stealing the preallocate range that is for
> gart_iommu_hole workaround.
>
> so restore the sequence...
>
> will get back
> [ 0.000000] Your BIOS doesn't leave a aperture memory hole
> [ 0.000000] Please enable the IOMMU option in the BIOS setup
> [ 0.000000] This costs you 64 MB of RAM
> [ 0.000000] Mapping aperture over 65536 KB of RAM @ 20000000
> ...
> [ 12.702822] calling pci_iommu_init+0x0/0x31 @ 1
> [ 12.708728] PCI-DMA: Disabling AGP.
> [ 12.712812] PCI-DMA: aperture base @ 20000000 size 65536 KB
> [ 12.718384] PCI-DMA: using GART IOMMU.
> [ 12.722139] PCI-DMA: Reserving 64MB of IOMMU area in the AGP aperture
> [ 12.736944] initcall pci_iommu_init+0x0/0x31 returned 0 after 28802 usecs
>
> -v2: call shutdown when no agp is there
> -v3: add check_store to restore state for swiotlb
> separate pci_swiotlb_detect and pci_swiotlb_init from FUJITA
>
> Signed-off-by: Yinghai Lu <yinghai@...nel.org>
>
> ---
> arch/x86/include/asm/swiotlb.h | 8 ++++++--
> arch/x86/kernel/aperture_64.c | 17 ++++++++++++++---
> arch/x86/kernel/pci-dma.c | 11 +++++++++--
> arch/x86/kernel/pci-gart_64.c | 3 ++-
> arch/x86/kernel/pci-swiotlb.c | 11 +++++++----
> 5 files changed, 38 insertions(+), 12 deletions(-)
>
> Index: linux-2.6/arch/x86/kernel/aperture_64.c
> ===================================================================
> --- linux-2.6.orig/arch/x86/kernel/aperture_64.c
> +++ linux-2.6/arch/x86/kernel/aperture_64.c
> @@ -375,6 +375,9 @@ void __init gart_iommu_hole_init(void)
> u64 aper_base, last_aper_base = 0;
> int fix, slot, valid_agp = 0;
> int i, node;
> + int iommu_detected_old = iommu_detected;
> + int gart_iommu_aperture_old = gart_iommu_aperture;
> + int (*iommu_init_old)(void) = x86_init.iommu.iommu_init;
This 'setting first and restoring later' code is hacky. It's better to
set only when we necessary.
> if (gart_iommu_aperture_disabled || !fix_aperture ||
> !early_pci_allowed())
> @@ -448,7 +451,7 @@ out:
>
> insert_aperture_resource((u32)last_aper_base, n);
> }
> - return;
> + goto check_restore;
> }
>
> if (!fallback_aper_force) {
> @@ -458,7 +461,7 @@ out:
>
> if (aper_alloc) {
> /* Got the aperture from the AGP bridge */
> - } else if (!valid_agp) {
> + } else if (swiotlb && !valid_agp) {
> /* Do nothing */
> } else if ((!no_iommu && max_pfn > MAX_DMA32_PFN) ||
> force_iommu ||
> @@ -486,7 +489,7 @@ out:
> panic("Not enough memory for aperture");
> }
> } else {
> - return;
> + goto check_restore;
> }
>
> /* Fix up the north bridges */
> @@ -510,4 +513,12 @@ out:
> }
>
> set_up_gart_resume(aper_order, aper_alloc);
> +
> +check_restore:
> + if (swiotlb) {
> + /* restore the setting */
> + iommu_detected = iommu_detected_old;
> + gart_iommu_aperture = gart_iommu_aperture_old;
> + x86_init.iommu.iommu_init = iommu_init_old;
> + }
> }
> Index: linux-2.6/arch/x86/kernel/pci-dma.c
> ===================================================================
> --- linux-2.6.orig/arch/x86/kernel/pci-dma.c
> +++ linux-2.6/arch/x86/kernel/pci-dma.c
> @@ -120,21 +120,28 @@ static void __init dma32_free_bootmem(vo
>
> void __init pci_iommu_alloc(void)
> {
> + int ret;
> +
> #ifdef CONFIG_X86_64
> /* free the range so iommu could get some range less than 4G */
> dma32_free_bootmem();
> #endif
> - if (pci_swiotlb_init())
> - return;
> + ret = pci_swiotlb_detect();
>
> gart_iommu_hole_init();
>
> + if (ret)
> + goto out;
> +
> detect_calgary();
>
> detect_intel_iommu();
>
> /* needs to be called after gart_iommu_hole_init */
> amd_iommu_detect();
> +
> +out:
> + pci_swiotlb_init();
> }
>
> void *dma_generic_alloc_coherent(struct device *dev, size_t size,
> Index: linux-2.6/arch/x86/kernel/pci-gart_64.c
> ===================================================================
> --- linux-2.6.orig/arch/x86/kernel/pci-gart_64.c
> +++ linux-2.6/arch/x86/kernel/pci-gart_64.c
> @@ -710,7 +710,8 @@ static void gart_iommu_shutdown(void)
> struct pci_dev *dev;
> int i;
>
> - if (no_agp)
> + /* don't shutdown it if there is AGP installed */
> + if (!no_agp)
> return;
>
> for (i = 0; i < num_k8_northbridges; i++) {
> Index: linux-2.6/arch/x86/include/asm/swiotlb.h
> ===================================================================
> --- linux-2.6.orig/arch/x86/include/asm/swiotlb.h
> +++ linux-2.6/arch/x86/include/asm/swiotlb.h
> @@ -5,13 +5,17 @@
>
> #ifdef CONFIG_SWIOTLB
> extern int swiotlb;
> -extern int pci_swiotlb_init(void);
> +int pci_swiotlb_detect(void);
> +void pci_swiotlb_init(void);
> #else
> #define swiotlb 0
> -static inline int pci_swiotlb_init(void)
> +static inline int pci_swiotlb_detect(void)
> {
> return 0;
> }
> +static inline void pci_swiotlb_init(void)
> +{
> +}
> #endif
>
> static inline void dma_mark_clean(void *addr, size_t size) {}
> Index: linux-2.6/arch/x86/kernel/pci-swiotlb.c
> ===================================================================
> --- linux-2.6.orig/arch/x86/kernel/pci-swiotlb.c
> +++ linux-2.6/arch/x86/kernel/pci-swiotlb.c
> @@ -43,12 +43,12 @@ static struct dma_map_ops swiotlb_dma_op
> };
>
> /*
> - * pci_swiotlb_init - initialize swiotlb if necessary
> + * pci_swiotlb_detect - initialize swiotlb if necessary
> *
> * This returns non-zero if we are forced to use swiotlb (by the boot
> * option).
> */
> -int __init pci_swiotlb_init(void)
> +int __init pci_swiotlb_detect(void)
> {
> int use_swiotlb = swiotlb | swiotlb_force;
>
> @@ -60,10 +60,13 @@ int __init pci_swiotlb_init(void)
> if (swiotlb_force)
> swiotlb = 1;
>
> + return use_swiotlb;
> +}
> +
> +void __init pci_swiotlb_init(void)
> +{
> if (swiotlb) {
> swiotlb_init(0);
> dma_ops = &swiotlb_dma_ops;
> }
> -
> - return use_swiotlb;
> }
>
>
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