Re: [PATCH v10 7/9] KVM: Update lpage info when private/shared memory are mixed
From: Chao Peng <hidden>
Date: 2023-01-28 14:03:01
Also in:
kvm, linux-arch, linux-doc, linux-fsdevel, linux-mm, lkml, qemu-devel
Subsystem:
kernel virtual machine for x86 (kvm/x86), the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Sean Christopherson, Paolo Bonzini, Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
On Fri, Jan 13, 2023 at 11:16:27PM +0000, Sean Christopherson wrote:
On Fri, Dec 02, 2022, Chao Peng wrote:quoted
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 9a07380f8d3c..5aefcff614d2 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c@@ -12362,6 +12362,8 @@ static int kvm_alloc_memslot_metadata(struct kvm *kvm, if ((slot->base_gfn + npages) & (KVM_PAGES_PER_HPAGE(level) - 1)) linfo[lpages - 1].disallow_lpage = 1; ugfn = slot->userspace_addr >> PAGE_SHIFT; + if (kvm_slot_can_be_private(slot)) + ugfn |= slot->restricted_offset >> PAGE_SHIFT; /* * If the gfn and userspace address are not aligned wrt each * other, disable large page support for this slot.Forgot to talk about the bug. This code needs to handle the scenario where a memslot is created with existing, non-uniform attributes. It might be a bit ugly (I didn't even try to write the code), but it's definitely possible, and since memslot updates are already slow I think it's best to handle things here. In the meantime, I added this so we don't forget to fix it before merging. #ifdef CONFIG_KVM_GENERIC_MEMORY_ATTRIBUTES pr_crit_once("FIXME: Walk the memory attributes of the slot and set the mixed status appropriately"); #endif
Here is the code to fix (based on your latest github repo).
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index e552374f2357..609ff1cba9c5 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h@@ -2195,4 +2195,9 @@ int memslot_rmap_alloc(struct kvm_memory_slot *slot, unsigned long npages); KVM_X86_QUIRK_FIX_HYPERCALL_INSN | \ KVM_X86_QUIRK_MWAIT_NEVER_UD_FAULTS) +#ifdef CONFIG_KVM_GENERIC_MEMORY_ATTRIBUTES +void kvm_memory_attributes_create_memslot(struct kvm *kvm, + struct kvm_memory_slot *slot); +#endif + #endif /* _ASM_X86_KVM_HOST_H */
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index eda615f3951c..8833d7201e41 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c@@ -7201,10 +7201,11 @@ static bool has_mixed_attrs(struct kvm *kvm, struct kvm_memory_slot *slot, return false; } -void kvm_arch_set_memory_attributes(struct kvm *kvm, - struct kvm_memory_slot *slot, - unsigned long attrs, - gfn_t start, gfn_t end) +static void kvm_update_lpage_mixed_flag(struct kvm *kvm, + struct kvm_memory_slot *slot, + bool set_attrs, + unsigned long attrs, + gfn_t start, gfn_t end) { unsigned long pages, mask; gfn_t gfn, gfn_end, first, last;
@@ -7231,25 +7232,53 @@ void kvm_arch_set_memory_attributes(struct kvm *kvm, first = start & mask; last = (end - 1) & mask; - /* - * We only need to scan the head and tail page, for middle pages - * we know they will not be mixed. - */ + /* head page */ gfn = max(first, slot->base_gfn); gfn_end = min(first + pages, slot->base_gfn + slot->npages); + if(!set_attrs) + attrs = kvm_get_memory_attributes(kvm, gfn); mixed = has_mixed_attrs(kvm, slot, level, attrs, gfn, gfn_end); linfo_update_mixed(gfn, slot, level, mixed); if (first == last) return; - for (gfn = first + pages; gfn < last; gfn += pages) - linfo_update_mixed(gfn, slot, level, false); + /* middle pages */ + for (gfn = first + pages; gfn < last; gfn += pages) { + if (set_attrs) { + mixed = false; + } else { + gfn_end = gfn + pages; + attrs = kvm_get_memory_attributes(kvm, gfn); + mixed = has_mixed_attrs(kvm, slot, level, attrs, + gfn, gfn_end); + } + linfo_update_mixed(gfn, slot, level, mixed); + } + /* tail page */ gfn = last; gfn_end = min(last + pages, slot->base_gfn + slot->npages); + if(!set_attrs) + attrs = kvm_get_memory_attributes(kvm, gfn); mixed = has_mixed_attrs(kvm, slot, level, attrs, gfn, gfn_end); linfo_update_mixed(gfn, slot, level, mixed); } } + +void kvm_arch_set_memory_attributes(struct kvm *kvm, + struct kvm_memory_slot *slot, + unsigned long attrs, + gfn_t start, gfn_t end) +{ + kvm_update_lpage_mixed_flag(kvm, slot, true, attrs, start, end); +} + +void kvm_memory_attributes_create_memslot(struct kvm *kvm, + struct kvm_memory_slot *slot) +{ + + kvm_update_lpage_mixed_flag(kvm, slot, false, 0, slot->base_gfn, + slot->base_gfn + slot->npages); +} #endif
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 268c3d16894d..c1074aecf2d0 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c@@ -12443,7 +12443,7 @@ static int kvm_alloc_memslot_metadata(struct kvm *kvm, } #ifdef CONFIG_KVM_GENERIC_MEMORY_ATTRIBUTES - pr_crit_once("FIXME: Walk the memory attributes of the slot and set the mixed status appropriately"); + kvm_memory_attributes_create_memslot(kvm, slot); #endif if (kvm_page_track_create_memslot(kvm, slot, npages))