We cannot access protected pages directly. Use ioremap() to create a temporary mapping of the page. The mapping is destroyed on __kvm_unmap_gfn().
The new interface gfn_to_pfn_memslot_protected() is used to detect if the page is protected. ioremap_cache_force() is a hack to bypass IORES_MAP_SYSTEM_RAM check in the x86 ioremap code. We need a better solution. Signed-off-by: Kirill A. Shutemov <[email protected]> --- arch/x86/include/asm/io.h | 2 ++ arch/x86/include/asm/pgtable_types.h | 1 + arch/x86/mm/ioremap.c | 16 +++++++++++++--- include/linux/kvm_host.h | 1 + virt/kvm/kvm_main.c | 14 +++++++++++--- 5 files changed, 28 insertions(+), 6 deletions(-) diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h index c58d52fd7bf2..a3e1bfad1026 100644 --- a/arch/x86/include/asm/io.h +++ b/arch/x86/include/asm/io.h @@ -184,6 +184,8 @@ extern void __iomem *ioremap_uc(resource_size_t offset, unsigned long size); #define ioremap_uc ioremap_uc extern void __iomem *ioremap_cache(resource_size_t offset, unsigned long size); #define ioremap_cache ioremap_cache +extern void __iomem *ioremap_cache_force(resource_size_t offset, unsigned long size); +#define ioremap_cache_force ioremap_cache_force extern void __iomem *ioremap_prot(resource_size_t offset, unsigned long size, unsigned long prot_val); #define ioremap_prot ioremap_prot extern void __iomem *ioremap_encrypted(resource_size_t phys_addr, unsigned long size); diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h index b6606fe6cfdf..66cc22abda7b 100644 --- a/arch/x86/include/asm/pgtable_types.h +++ b/arch/x86/include/asm/pgtable_types.h @@ -147,6 +147,7 @@ enum page_cache_mode { _PAGE_CACHE_MODE_UC = 3, _PAGE_CACHE_MODE_WT = 4, _PAGE_CACHE_MODE_WP = 5, + _PAGE_CACHE_MODE_WB_FORCE = 6, _PAGE_CACHE_MODE_NUM = 8 }; diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c index 18c637c0dc6f..e48fc0e130b2 100644 --- a/arch/x86/mm/ioremap.c +++ b/arch/x86/mm/ioremap.c @@ -202,9 +202,12 @@ __ioremap_caller(resource_size_t phys_addr, unsigned long size, __ioremap_check_mem(phys_addr, size, &io_desc); /* - * Don't allow anybody to remap normal RAM that we're using.. + * Don't allow anybody to remap normal RAM that we're using, unless + * _PAGE_CACHE_MODE_WB_FORCE is used. */ - if (io_desc.flags & IORES_MAP_SYSTEM_RAM) { + if (pcm == _PAGE_CACHE_MODE_WB_FORCE) { + pcm = _PAGE_CACHE_MODE_WB; + } else if (io_desc.flags & IORES_MAP_SYSTEM_RAM) { WARN_ONCE(1, "ioremap on RAM at %pa - %pa\n", &phys_addr, &last_addr); return NULL; @@ -419,6 +422,13 @@ void __iomem *ioremap_cache(resource_size_t phys_addr, unsigned long size) } EXPORT_SYMBOL(ioremap_cache); +void __iomem *ioremap_cache_force(resource_size_t phys_addr, unsigned long size) +{ + return __ioremap_caller(phys_addr, size, _PAGE_CACHE_MODE_WB_FORCE, + __builtin_return_address(0), false); +} +EXPORT_SYMBOL(ioremap_cache_force); + void __iomem *ioremap_prot(resource_size_t phys_addr, unsigned long size, unsigned long prot_val) { @@ -467,7 +477,7 @@ void iounmap(volatile void __iomem *addr) p = find_vm_area((void __force *)addr); if (!p) { - printk(KERN_ERR "iounmap: bad address %p\n", addr); + printk(KERN_ERR "iounmap: bad address %px\n", addr); dump_stack(); return; } diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index eca18ef9b1f4..b6944f88033d 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -237,6 +237,7 @@ struct kvm_host_map { void *hva; kvm_pfn_t pfn; kvm_pfn_t gfn; + bool protected; }; /* diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 8bcf3201304a..71aac117357f 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -2091,6 +2091,7 @@ static int __kvm_map_gfn(struct kvm_memslots *slots, gfn_t gfn, void *hva = NULL; struct page *page = KVM_UNMAPPED_PAGE; struct kvm_memory_slot *slot = __gfn_to_memslot(slots, gfn); + bool protected = false; u64 gen = slots->generation; if (!map) @@ -2107,12 +2108,16 @@ static int __kvm_map_gfn(struct kvm_memslots *slots, gfn_t gfn, } else { if (atomic) return -EAGAIN; - pfn = gfn_to_pfn_memslot(slot, gfn); + pfn = gfn_to_pfn_memslot_protected(slot, gfn, &protected); } if (is_error_noslot_pfn(pfn)) return -EINVAL; - if (pfn_valid(pfn)) { + if (protected) { + if (atomic) + return -EAGAIN; + hva = ioremap_cache_force(pfn_to_hpa(pfn), PAGE_SIZE); + } else if (pfn_valid(pfn)) { page = pfn_to_page(pfn); if (atomic) hva = kmap_atomic(page); @@ -2133,6 +2138,7 @@ static int __kvm_map_gfn(struct kvm_memslots *slots, gfn_t gfn, map->hva = hva; map->pfn = pfn; map->gfn = gfn; + map->protected = protected; return 0; } @@ -2163,7 +2169,9 @@ static void __kvm_unmap_gfn(struct kvm_memory_slot *memslot, if (!map->hva) return; - if (map->page != KVM_UNMAPPED_PAGE) { + if (map->protected) { + iounmap(map->hva); + } else if (map->page != KVM_UNMAPPED_PAGE) { if (atomic) kunmap_atomic(map->hva); else -- 2.26.2
