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73 lines
2.3 KiB
73 lines
2.3 KiB
From 433928d3823f561919ead305194e46e5311b573d Mon Sep 17 00:00:00 2001
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From: Marek Marczykowski <marmarek@invisiblethingslab.com>
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Date: Sat, 23 Jun 2012 19:50:44 +0200
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Subject: [PATCH 1/2] Revert "xen/pat: Disable PAT support for now."
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Organization: Invisible Things Lab
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This reverts commit 8eaffa67b43e99ae581622c5133e20b0f48bcef1.
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We haven't observed failure which is workarounded by this patch, but it caused
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horrible GPU performance. Anyway there is "nopat" option.
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Signed-off-by: Marek Marczykowski <marmarek@invisiblethingslab.com>
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---
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arch/x86/xen/enlighten.c | 2 --
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arch/x86/xen/mmu.c | 8 ++++----
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2 files changed, 4 insertions(+), 6 deletions(-)
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diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
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index 6c7f1e8..bf3319c 100644
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--- a/arch/x86/xen/enlighten.c
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+++ b/arch/x86/xen/enlighten.c
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@@ -1269,9 +1269,7 @@ asmlinkage void __init xen_start_kernel(void)
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/* Prevent unwanted bits from being set in PTEs. */
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__supported_pte_mask &= ~_PAGE_GLOBAL;
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-#if 0
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if (!xen_initial_domain())
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-#endif
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__supported_pte_mask &= ~(_PAGE_PWT | _PAGE_PCD);
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__supported_pte_mask |= _PAGE_IOMAP;
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diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
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index 69f5857..a5d252a 100644
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--- a/arch/x86/xen/mmu.c
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+++ b/arch/x86/xen/mmu.c
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@@ -420,13 +420,13 @@ static pteval_t iomap_pte(pteval_t val)
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static pteval_t xen_pte_val(pte_t pte)
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{
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pteval_t pteval = pte.pte;
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-#if 0
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+
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/* If this is a WC pte, convert back from Xen WC to Linux WC */
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if ((pteval & (_PAGE_PAT | _PAGE_PCD | _PAGE_PWT)) == _PAGE_PAT) {
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WARN_ON(!pat_enabled);
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pteval = (pteval & ~_PAGE_PAT) | _PAGE_PWT;
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}
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-#endif
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+
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if (xen_initial_domain() && (pteval & _PAGE_IOMAP))
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return pteval;
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@@ -468,7 +468,7 @@ void xen_set_pat(u64 pat)
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static pte_t xen_make_pte(pteval_t pte)
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{
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phys_addr_t addr = (pte & PTE_PFN_MASK);
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-#if 0
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+
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/* If Linux is trying to set a WC pte, then map to the Xen WC.
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* If _PAGE_PAT is set, then it probably means it is really
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* _PAGE_PSE, so avoid fiddling with the PAT mapping and hope
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@@ -481,7 +481,7 @@ static pte_t xen_make_pte(pteval_t pte)
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if ((pte & (_PAGE_PCD | _PAGE_PWT)) == _PAGE_PWT)
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pte = (pte & ~(_PAGE_PCD | _PAGE_PWT)) | _PAGE_PAT;
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}
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-#endif
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+
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/*
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* Unprivileged domains are allowed to do IOMAPpings for
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* PCI passthrough, but not map ISA space. The ISA
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--
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1.7.4.4
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