linux-kernel - [RESEND PATCH v10 08/10] mmu: spp: Handle SPP protected pages when VM memory changes

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Date:   Thu,  2 Jan 2020 13:19:02 +0800
From:   Yang Weijiang <weijiang.yang@...el.com>
To:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        pbonzini@...hat.com, jmattson@...gle.com,
        sean.j.christopherson@...el.com
Cc:     yu.c.zhang@...ux.intel.com, alazar@...defender.com,
        edwin.zhai@...el.com, Yang Weijiang <weijiang.yang@...el.com>
Subject: [RESEND PATCH v10 08/10] mmu: spp: Handle SPP protected pages when VM memory changes

Host page swapping/migration may change the translation in
EPT leaf entry, if the target page is SPP protected,
re-enable SPP protection in MMU notifier. If SPPT shadow
page is reclaimed, the level1 pages don't have rmap to clear.

Signed-off-by: Yang Weijiang <weijiang.yang@...el.com>
---
 arch/x86/kvm/mmu/mmu.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index aada0a3552b2..3fcc6ee71f15 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -1913,6 +1913,19 @@ static int kvm_set_pte_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head,
 			new_spte &= ~PT_WRITABLE_MASK;
 			new_spte &= ~SPTE_HOST_WRITEABLE;
 
+			/*
+			 * if it's EPT leaf entry and the physical page is
+			 * SPP protected, then re-enable SPP protection for
+			 * the page.
+			 */
+			if (kvm->arch.spp_active &&
+			    level == PT_PAGE_TABLE_LEVEL) {
+				u32 *access = gfn_to_subpage_wp_info(slot, gfn);
+
+				if (access && *access != FULL_SPP_ACCESS)
+					new_spte |= PT_SPP_MASK;
+			}
+
 			new_spte = mark_spte_for_access_track(new_spte);
 
 			mmu_spte_clear_track_bits(sptep);
@@ -2763,6 +2776,10 @@ static bool mmu_page_zap_pte(struct kvm *kvm, struct kvm_mmu_page *sp,
 	pte = *spte;
 	if (is_shadow_present_pte(pte)) {
 		if (is_last_spte(pte, sp->role.level)) {
+			/* SPPT leaf entries don't have rmaps*/
+			if (sp->role.level == PT_PAGE_TABLE_LEVEL &&
+			    is_spp_spte(sp))
+				return true;
 			drop_spte(kvm, spte);
 			if (is_large_pte(pte))
 				--kvm->stat.lpages;
-- 
2.17.2