From 7f2f88224517cdaad68b772b2a2095b87dc72886 Mon Sep 17 00:00:00 2001 From: David Vrabel Date: Wed, 8 Jan 2014 14:01:01 +0000 Subject: [PATCH] x86/xen: do not use _PAGE_IOMAP PTE flag for I/O mappings Since mfn_to_pfn() returns the correct PFN for identity mappings (as used for MMIO regions), the use of _PAGE_IOMAP is not required in pte_mfn_to_pfn(). Do not set the _PAGE_IOMAP flag in pte_pfn_to_mfn() and do not use it in pte_mfn_to_pfn(). This will allow _PAGE_IOMAP to be removed, making it available for future use. Signed-off-by: David Vrabel Reviewed-by: Konrad Rzeszutek Wilk --- arch/x86/xen/mmu.c | 48 ++++-------------------------------------------- 1 file changed, 4 insertions(+), 44 deletions(-) diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c index 16fb0099b7f2..f62af7647ec9 100644 --- a/arch/x86/xen/mmu.c +++ b/arch/x86/xen/mmu.c @@ -399,38 +399,14 @@ static pteval_t pte_pfn_to_mfn(pteval_t val) if (unlikely(mfn == INVALID_P2M_ENTRY)) { mfn = 0; flags = 0; - } else { - /* - * Paramount to do this test _after_ the - * INVALID_P2M_ENTRY as INVALID_P2M_ENTRY & - * IDENTITY_FRAME_BIT resolves to true. - */ - mfn &= ~FOREIGN_FRAME_BIT; - if (mfn & IDENTITY_FRAME_BIT) { - mfn &= ~IDENTITY_FRAME_BIT; - flags |= _PAGE_IOMAP; - } - } + } else + mfn &= ~(FOREIGN_FRAME_BIT | IDENTITY_FRAME_BIT); val = ((pteval_t)mfn << PAGE_SHIFT) | flags; } return val; } -static pteval_t iomap_pte(pteval_t val) -{ - if (val & _PAGE_PRESENT) { - unsigned long pfn = (val & PTE_PFN_MASK) >> PAGE_SHIFT; - pteval_t flags = val & PTE_FLAGS_MASK; - - /* We assume the pte frame number is a MFN, so - just use it as-is. */ - val = ((pteval_t)pfn << PAGE_SHIFT) | flags; - } - - return val; -} - __visible pteval_t xen_pte_val(pte_t pte) { pteval_t pteval = pte.pte; @@ -441,9 +417,6 @@ __visible pteval_t xen_pte_val(pte_t pte) pteval = (pteval & ~_PAGE_PAT) | _PAGE_PWT; } #endif - if (xen_initial_domain() && (pteval & _PAGE_IOMAP)) - return pteval; - return pte_mfn_to_pfn(pteval); } PV_CALLEE_SAVE_REGS_THUNK(xen_pte_val); @@ -481,7 +454,6 @@ void xen_set_pat(u64 pat) __visible pte_t xen_make_pte(pteval_t pte) { - phys_addr_t addr = (pte & PTE_PFN_MASK); #if 0 /* If Linux is trying to set a WC pte, then map to the Xen WC. * If _PAGE_PAT is set, then it probably means it is really @@ -496,19 +468,7 @@ __visible pte_t xen_make_pte(pteval_t pte) pte = (pte & ~(_PAGE_PCD | _PAGE_PWT)) | _PAGE_PAT; } #endif - /* - * Unprivileged domains are allowed to do IOMAPpings for - * PCI passthrough, but not map ISA space. The ISA - * mappings are just dummy local mappings to keep other - * parts of the kernel happy. - */ - if (unlikely(pte & _PAGE_IOMAP) && - (xen_initial_domain() || addr >= ISA_END_ADDRESS)) { - pte = iomap_pte(pte); - } else { - pte &= ~_PAGE_IOMAP; - pte = pte_pfn_to_mfn(pte); - } + pte = pte_pfn_to_mfn(pte); return native_make_pte(pte); } @@ -2091,7 +2051,7 @@ static void xen_set_fixmap(unsigned idx, phys_addr_t phys, pgprot_t prot) default: /* By default, set_fixmap is used for hardware mappings */ - pte = mfn_pte(phys, __pgprot(pgprot_val(prot) | _PAGE_IOMAP)); + pte = mfn_pte(phys, prot); break; } -- 2.11.0