KVM: x86/mmu: Map TDP MMU leaf SPTE iff target level is reached

------------[ cut here ]------------ WARNING: CPU: 1 PID: 1025 at arch/x86/kvm/mmu/tdp_mmu.c:1070 kvm_tdp_mmu_map+0x481/0x510 Modules linked in: kvm_intel CPU: 1 PID: 1025 Comm: nx_huge_pages_t Tainted: G W 6.1.0-rc4+ torvalds#64 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 RIP: 0010:kvm_tdp_mmu_map+0x481/0x510 RSP: 0018:ffffc9000072fba8 EFLAGS: 00010286 RAX: 0000000000000000 RBX: ffffc9000072fcc0 RCX: 0000000000000027 RDX: 0000000000000027 RSI: 00000000ffffdfff RDI: ffff888277c5b4c8 RBP: ffff888107d45a10 R08: ffff888277c5b4c0 R09: ffffc9000072fa48 R10: 0000000000000001 R11: 0000000000000001 R12: ffffc9000073a0e0 R13: ffff88810fc54800 R14: ffff888107d1ae60 R15: ffff88810fc54f90 FS: 00007fba9f853740(0000) GS:ffff888277c40000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 000000010aa7a003 CR4: 0000000000172ea0 Call Trace: <TASK> kvm_tdp_page_fault+0x10c/0x130 kvm_mmu_page_fault+0x103/0x680 vmx_handle_exit+0x132/0x5a0 [kvm_intel] vcpu_enter_guest+0x60c/0x16f0 kvm_arch_vcpu_ioctl_run+0x1e2/0x9d0 kvm_vcpu_ioctl+0x271/0x660 __x64_sys_ioctl+0x80/0xb0 do_syscall_64+0x2b/0x50 entry_SYSCALL_64_after_hwframe+0x46/0xb0 </TASK> ---[ end trace 0000000000000000 ]--- Invalid SPTE change: cannot replace a present leaf SPTE with another present leaf SPTE mapping a different PFN! as_id: 0 gfn: 100200 old_spte: 600000112400bf3 new_spte: 6000001126009f3 level: 2 ------------[ cut here ]------------ kernel BUG at arch/x86/kvm/mmu/tdp_mmu.c:559! invalid opcode: 0000 [#1] SMP CPU: 1 PID: 1025 Comm: nx_huge_pages_t Tainted: G W 6.1.0-rc4+ torvalds#64 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 RIP: 0010:__handle_changed_spte.cold+0x95/0x9c RSP: 0018:ffffc9000072faf8 EFLAGS: 00010246 RAX: 00000000000000c1 RBX: ffffc90000731000 RCX: 0000000000000027 RDX: 0000000000000000 RSI: 00000000ffffdfff RDI: ffff888277c5b4c8 RBP: 0600000112400bf3 R08: ffff888277c5b4c0 R09: ffffc9000072f9a0 R10: 0000000000000001 R11: 0000000000000001 R12: 06000001126009f3 R13: 0000000000000002 R14: 0000000012600901 R15: 0000000012400b01 FS: 00007fba9f853740(0000) GS:ffff888277c40000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 000000010aa7a003 CR4: 0000000000172ea0 Call Trace: <TASK> kvm_tdp_mmu_map+0x3b0/0x510 kvm_tdp_page_fault+0x10c/0x130 kvm_mmu_page_fault+0x103/0x680 vmx_handle_exit+0x132/0x5a0 [kvm_intel] vcpu_enter_guest+0x60c/0x16f0 kvm_arch_vcpu_ioctl_run+0x1e2/0x9d0 kvm_vcpu_ioctl+0x271/0x660 __x64_sys_ioctl+0x80/0xb0 do_syscall_64+0x2b/0x50 entry_SYSCALL_64_after_hwframe+0x46/0xb0 </TASK> Modules linked in: kvm_intel ---[ end trace 0000000000000000 ]--- Signed-off-by: Sean Christopherson <[email protected]>
sean-jc · Dec 9, 2022 · 265bc58 · 265bc58
1 parent 47c0b6c
commit 265bc58
Showing 1 changed file with 11 additions and 3 deletions.
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -1170,7 +1170,7 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
 			goto retry;
 
 		if (iter.level == fault->goal_level)
-			break;
+			goto map_target_level;
 
 		/* Step down into the lower level page table if it exists. */
 		if (is_shadow_present_pte(iter.old_spte) &&
@@ -1192,8 +1192,8 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
 			r = tdp_mmu_link_sp(kvm, &iter, sp, true);
 
 		/*
-		 * Also force the guest to retry the access if the upper level SPTEs
-		 * aren't in place.
+		 * Force the guest to retry if installing an upper level SPTE
+		 * failed, e.g. because a different task modified the SPTE.
 		 */
 		if (r) {
 			tdp_mmu_free_sp(sp);
@@ -1208,6 +1208,14 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
 		}
 	}
 
+	/*
+	 * The walk aborted before reaching the target level, e.g. because the
+	 * iterator detected an upper level SPTE was frozen during traversal.
+	 */
+	WARN_ON_ONCE(iter.level == fault->goal_level);
+	goto retry;
+
+map_target_level:
 	ret = tdp_mmu_map_handle_target_level(vcpu, fault, &iter);
 
 retry: