pfn_valid check is not sufficient because it only checks if a page has a struct page or not, if for example "mem=" was passed to the kernel some valid pages won't have a struct page. This means that if guests were assigned valid memory that lies after the mem= boundary it will be passed uncached to the guest no matter what the guest caching attributes are for this memory.
Use the original e820 map to check whether a certain pfn belongs to RAM or not. Cc: Thomas Gleixner <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: H. Peter Anvin <[email protected]> Cc: Paolo Bonzini <[email protected]> Cc: Radim Krčmář <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Denys Vlasenko <[email protected]> Cc: Andrew Morton <[email protected]> Cc: Toshi Kani <[email protected]> Cc: Tony Luck <[email protected]> Cc: [email protected] Cc: [email protected] Cc: [email protected] Signed-off-by: KarimAllah Ahmed <[email protected]> --- arch/x86/include/asm/e820.h | 1 + arch/x86/kernel/e820.c | 18 ++++++++++++++++++ arch/x86/kvm/mmu.c | 2 +- 3 files changed, 20 insertions(+), 1 deletion(-) diff --git a/arch/x86/include/asm/e820.h b/arch/x86/include/asm/e820.h index 3ab0537..2d4f7d8 100644 --- a/arch/x86/include/asm/e820.h +++ b/arch/x86/include/asm/e820.h @@ -16,6 +16,7 @@ extern struct e820map e820_saved; extern unsigned long pci_mem_start; extern int e820_any_mapped(u64 start, u64 end, unsigned type); extern int e820_all_mapped(u64 start, u64 end, unsigned type); +extern bool e820_is_ram(u64 addr); extern void e820_add_region(u64 start, u64 size, int type); extern void e820_print_map(char *who); extern int diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c index 621b501..387cdba 100644 --- a/arch/x86/kernel/e820.c +++ b/arch/x86/kernel/e820.c @@ -105,6 +105,24 @@ int __init e820_all_mapped(u64 start, u64 end, unsigned type) return 0; } +bool +e820_is_ram(u64 addr) +{ + int i; + + for (i = 0; i < e820_saved.nr_map; i++) { + struct e820entry *ei = &e820_saved.map[i]; + + if (ei->type != E820_RAM) + continue; + if ((addr >= ei->addr) && (addr < (ei->addr + ei->size))) + return true; + } + + return false; +} +EXPORT_SYMBOL_GPL(e820_is_ram); + /* * Add a memory region to the kernel e820 map. */ diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index 24e8001..5e07bf5 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -2507,7 +2507,7 @@ static bool kvm_is_mmio_pfn(kvm_pfn_t pfn) if (pfn_valid(pfn)) return !is_zero_pfn(pfn) && PageReserved(pfn_to_page(pfn)); - return true; + return !e820_is_ram(pfn << PAGE_SHIFT); } static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep, -- 2.8.2
