lkml.org 
[lkml]   [2020]   [Sep]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[RFC V2 3/9] Introduce page table remove function for direct build EPT feature
Date
From: Yulei Zhang <yuleixzhang@tencent.com>

During guest boots up it will modify the memory slots multiple times,
so add page table remove function to free pre-pinned memory according
to the the memory slot changes.

Signed-off-by: Yulei Zhang <yuleixzhang@tencent.com>
---
arch/x86/kvm/mmu/mmu.c | 56 ++++++++++++++++++++++++++++++++++++++++++
1 file changed, 56 insertions(+)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index bfe4d2b3e809..03c5e73b96cb 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -6482,6 +6482,62 @@ int kvm_direct_tdp_populate_page_table(struct kvm *kvm, struct kvm_memory_slot *
return 0;
}

+static int __kvm_remove_spte(struct kvm *kvm, u64 *addr, gfn_t gfn, int level)
+{
+ int i;
+ int ret = level;
+ bool present = false;
+ kvm_pfn_t pfn;
+ u64 *sptep = (u64 *)__va((*addr) & PT64_BASE_ADDR_MASK);
+ unsigned index = SHADOW_PT_INDEX(gfn << PAGE_SHIFT, level);
+
+ for (i = 0; i < PT64_ENT_PER_PAGE; ++i) {
+ if (is_shadow_present_pte(sptep[i])) {
+ if (i == index) {
+ if (!is_last_spte(sptep[i], level)) {
+ ret = __kvm_remove_spte(kvm, &sptep[i], gfn, level - 1);
+ if (is_shadow_present_pte(sptep[i]))
+ return ret;
+ } else {
+ pfn = spte_to_pfn(sptep[i]);
+ mmu_spte_clear_track_bits(&sptep[i]);
+ kvm_release_pfn_clean(pfn);
+ if (present)
+ return ret;
+ }
+ } else {
+ if (i > index)
+ return ret;
+ else
+ present = true;
+ }
+ }
+ }
+
+ if (!present) {
+ pfn = spte_to_pfn(*addr);
+ mmu_spte_clear_track_bits(addr);
+ kvm_release_pfn_clean(pfn);
+ }
+ return ret;
+}
+
+void kvm_direct_tdp_remove_page_table(struct kvm *kvm, struct kvm_memory_slot *slot)
+{
+ gfn_t gfn = slot->base_gfn;
+ int host_level;
+
+ if (!kvm->arch.global_root_hpa)
+ return;
+
+ for (gfn = slot->base_gfn;
+ gfn < slot->base_gfn + slot->npages;
+ gfn += KVM_PAGES_PER_HPAGE(host_level))
+ host_level = __kvm_remove_spte(kvm, &(kvm->arch.global_root_hpa), gfn, PT64_ROOT_4LEVEL);
+
+ kvm_flush_remote_tlbs(kvm);
+}
+
/*
* Calculate mmu pages needed for kvm.
*/
--
2.17.1
\
 
 \ /
  Last update: 2020-09-01 14:06    [W:0.091 / U:2.288 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site