fix: clear private flag after freeing gmem folio

Not clearing the private flag causes it to stick around after freeing,
potentially confusing subsequent users of the folio that assign meaning
to the private flag.

Signed-off-by: Patrick Roy <[email protected]>

Author: roypat

resources/hiding_ci/linux_patches/10-direct-map-removal/0011-KVM-guest_memfd-Add-flag-to-remove-from-direct-map.patch

@@ -1,7 +1,7 @@
-From b1fc478976c93fd42b14e06d2de57e121be03142 Mon Sep 17 00:00:00 2001
+From a06590a8007e35c86caf7344f76e69d4501bc43a Mon Sep 17 00:00:00 2001
 From: Patrick Roy <[email protected]>
 Date: Fri, 7 Feb 2025 14:33:01 +0000
-Subject: [PATCH 11/26] KVM: guest_memfd: Add flag to remove from direct map
+Subject: [PATCH] KVM: guest_memfd: Add flag to remove from direct map
 
 Add KVM_GMEM_NO_DIRECT_MAP flag for KVM_CREATE_GUEST_MEMFD() ioctl. When
 set, guest_memfd folios will be removed from the direct map after
@@ -56,9 +56,9 @@ spectre-gadget.
 Signed-off-by: Patrick Roy <[email protected]>
 ---
  include/uapi/linux/kvm.h |  3 +++
- virt/kvm/guest_memfd.c   | 28 +++++++++++++++++++++++++++-
+ virt/kvm/guest_memfd.c   | 38 +++++++++++++++++++++++++++++++++-----
  virt/kvm/kvm_main.c      |  5 +++++
- 3 files changed, 35 insertions(+), 1 deletion(-)
+ 3 files changed, 41 insertions(+), 5 deletions(-)
 
 diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
 index 117937a895da..fb02a93546d8 100644
@@ -82,7 +82,7 @@ index 117937a895da..fb02a93546d8 100644
 
  struct kvm_pre_fault_memory {
 diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c
-index fbf89e643add..a2b96bc51391 100644
+index fbf89e643add..5545a35ce900 100644
 --- a/virt/kvm/guest_memfd.c
 +++ b/virt/kvm/guest_memfd.c
 @@ -4,6 +4,7 @@
@@ -117,18 +117,42 @@ index fbf89e643add..a2b96bc51391 100644
  	folio_mark_uptodate(folio);
  }
 
-@@ -478,6 +494,10 @@ static void kvm_gmem_free_folio(struct folio *folio)
+@@ -471,24 +487,30 @@ static int kvm_gmem_error_folio(struct address_space *mapping, struct folio *fol
+ 	return MF_DELAYED;
+ }
+ 
+-#ifdef CONFIG_HAVE_KVM_ARCH_GMEM_INVALIDATE
+ static void kvm_gmem_free_folio(struct folio *folio)
+ {
++#ifdef CONFIG_HAVE_KVM_ARCH_GMEM_INVALIDATE
+ 	struct page *page = folio_page(folio, 0);
  	kvm_pfn_t pfn = page_to_pfn(page);
  	int order = folio_order(folio);
++#endif
 
-+	if (folio_test_private(folio))
++	if (folio_test_private(folio)) {
 +		WARN_ON_ONCE(set_direct_map_valid_noflush(folio_page(folio, 0),
 +							  folio_nr_pages(folio), true));
++		folio_clear_private(folio);
++	}
 +
++#ifdef CONFIG_HAVE_KVM_ARCH_GMEM_INVALIDATE
  	kvm_arch_gmem_invalidate(pfn, pfn + (1ul << order));
- }
+-}
  #endif
-@@ -551,6 +571,9 @@ static int __kvm_gmem_create(struct kvm *kvm, loff_t size, u64 flags)
++}
+ 
+ static const struct address_space_operations kvm_gmem_aops = {
+ 	.dirty_folio = noop_dirty_folio,
+ 	.migrate_folio	= kvm_gmem_migrate_folio,
+ 	.error_remove_folio = kvm_gmem_error_folio,
+-#ifdef CONFIG_HAVE_KVM_ARCH_GMEM_INVALIDATE
+ 	.free_folio = kvm_gmem_free_folio,
+-#endif
+ };
+ 
+ static int kvm_gmem_getattr(struct mnt_idmap *idmap, const struct path *path,
+@@ -551,6 +573,9 @@ static int __kvm_gmem_create(struct kvm *kvm, loff_t size, u64 flags)
  	/* Unmovable mappings are supposed to be marked unevictable as well. */
  	WARN_ON_ONCE(!mapping_unevictable(inode->i_mapping));
 
@@ -138,7 +162,7 @@ index fbf89e643add..a2b96bc51391 100644
  	kvm_get_kvm(kvm);
  	gmem->kvm = kvm;
  	xa_init(&gmem->bindings);
-@@ -570,7 +593,10 @@ int kvm_gmem_create(struct kvm *kvm, struct kvm_create_guest_memfd *args)
+@@ -570,7 +595,10 @@ int kvm_gmem_create(struct kvm *kvm, struct kvm_create_guest_memfd *args)
  {
  	loff_t size = args->size;
  	u64 flags = args->flags;
@@ -174,5 +198,5 @@ index 3e40acb9f5c0..32ca1c921ab0 100644
  		return !kvm || kvm_arch_has_private_mem(kvm);
  #endif
 -- 
-2.47.1
+2.49.0
 

resources/hiding_ci/linux_patches/10-direct-map-removal/0012-fixup-for-direct-map-removal-v4.patch

@@ -1,32 +1,32 @@
-From f6c3a183801123395e05959b7a6508bf420eb726 Mon Sep 17 00:00:00 2001
+From e7b85181cec682a351825e7af734a8b1805d9ae3 Mon Sep 17 00:00:00 2001
 From: Patrick Roy <[email protected]>
-Date: Tue, 3 Jun 2025 13:57:15 +0100
+Date: Tue, 3 Jun 2025 14:55:28 +0100
 Subject: [PATCH] de-gpc-ify kvm-clock
 
 Signed-off-by: Patrick Roy <[email protected]>
 ---
  arch/x86/include/asm/kvm_host.h |  2 +-
- arch/x86/kvm/x86.c              | 47 ++++++++++-----------------------
- 2 files changed, 15 insertions(+), 34 deletions(-)
+ arch/x86/kvm/x86.c              | 63 ++++++++++-----------------------
+ 2 files changed, 20 insertions(+), 45 deletions(-)
 
 diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
-index ce9ad4cd93c5..6b2e9c2ee599 100644
+index b874e54a5ee4..7cdef9002af8 100644
 --- a/arch/x86/include/asm/kvm_host.h
 +++ b/arch/x86/include/asm/kvm_host.h
-@@ -915,7 +915,7 @@ struct kvm_vcpu_arch {
- 	s8  pvclock_tsc_shift;
- 	u32 pvclock_tsc_mul;
+@@ -911,7 +911,7 @@ struct kvm_vcpu_arch {
+ 	gpa_t time;
+ 	struct pvclock_vcpu_time_info hv_clock;
  	unsigned int hw_tsc_khz;
 -	struct gfn_to_pfn_cache pv_time;
 +	gpa_t system_time;
  	/* set guest stopped flag in pvclock flags field */
  	bool pvclock_set_guest_stopped_request;
 
 diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
-index 2a02f2457c42..5aad662ec0e1 100644
+index 4b64ab350bcd..5198d3e0fc81 100644
 --- a/arch/x86/kvm/x86.c
 +++ b/arch/x86/kvm/x86.c
-@@ -2333,12 +2333,9 @@ static void kvm_write_system_time(struct kvm_vcpu *vcpu, gpa_t system_time,
+@@ -2326,12 +2326,9 @@ static void kvm_write_system_time(struct kvm_vcpu *vcpu, gpa_t system_time,
 
  	/* we verify if the enable bit is set... */
  	if (system_time & 1)
@@ -41,90 +41,98 @@ index 2a02f2457c42..5aad662ec0e1 100644
  }
 
  static uint32_t div_frac(uint32_t dividend, uint32_t divisor)
-@@ -3132,26 +3129,14 @@ u64 get_kvmclock_ns(struct kvm *kvm)
+@@ -3116,26 +3113,16 @@ u64 get_kvmclock_ns(struct kvm *kvm)
+ 	return data.clock;
+ }
 
- static void kvm_setup_guest_pvclock(struct pvclock_vcpu_time_info *ref_hv_clock,
- 				    struct kvm_vcpu *vcpu,
+-static void kvm_setup_guest_pvclock(struct kvm_vcpu *v,
 -				    struct gfn_to_pfn_cache *gpc,
--				    unsigned int offset)
+-				    unsigned int offset,
+-				    bool force_tsc_unstable)
++static void kvm_setup_guest_pvclock(struct pvclock_vcpu_time_info *ref_hv_clock,
++				    struct kvm_vcpu *vcpu,
 +				    gpa_t gpa)
  {
+-	struct kvm_vcpu_arch *vcpu = &v->arch;
 -	struct pvclock_vcpu_time_info *guest_hv_clock;
-+	struct pvclock_vcpu_time_info guest_hv_clock;
- 	struct pvclock_vcpu_time_info hv_clock;
 -	unsigned long flags;
- 
- 	memcpy(&hv_clock, ref_hv_clock, sizeof(hv_clock));
- 
+-
 -	read_lock_irqsave(&gpc->lock, flags);
 -	while (!kvm_gpc_check(gpc, offset + sizeof(*guest_hv_clock))) {
 -		read_unlock_irqrestore(&gpc->lock, flags);
 -
 -		if (kvm_gpc_refresh(gpc, offset + sizeof(*guest_hv_clock)))
 -			return;
--
++	struct pvclock_vcpu_time_info guest_hv_clock;
++	struct pvclock_vcpu_time_info hv_clock;
+ 
 -		read_lock_irqsave(&gpc->lock, flags);
 -	}
--
++	memcpy(&hv_clock, ref_hv_clock, sizeof(hv_clock));
+ 
 -	guest_hv_clock = (void *)(gpc->khva + offset);
 +	kvm_read_guest(vcpu->kvm, gpa, &guest_hv_clock, sizeof(struct pvclock_vcpu_time_info));
 
  	/*
  	 * This VCPU is paused, but it's legal for a guest to read another
-@@ -3160,20 +3145,18 @@ static void kvm_setup_guest_pvclock(struct pvclock_vcpu_time_info *ref_hv_clock,
+@@ -3144,30 +3131,20 @@ static void kvm_setup_guest_pvclock(struct kvm_vcpu *v,
  	 * it is consistent.
  	 */
 
--	guest_hv_clock->version = hv_clock.version = (guest_hv_clock->version + 1) | 1;
+-	guest_hv_clock->version = vcpu->hv_clock.version = (guest_hv_clock->version + 1) | 1;
 +	guest_hv_clock.version = hv_clock.version = (guest_hv_clock.version + 1) | 1;
  	smp_wmb();
 
  	/* retain PVCLOCK_GUEST_STOPPED if set in guest copy */
--	hv_clock.flags |= (guest_hv_clock->flags & PVCLOCK_GUEST_STOPPED);
+-	vcpu->hv_clock.flags |= (guest_hv_clock->flags & PVCLOCK_GUEST_STOPPED);
+-
+-	if (vcpu->pvclock_set_guest_stopped_request) {
+-		vcpu->hv_clock.flags |= PVCLOCK_GUEST_STOPPED;
+-		vcpu->pvclock_set_guest_stopped_request = false;
+-	}
 +	hv_clock.flags |= (guest_hv_clock.flags & PVCLOCK_GUEST_STOPPED);
 
--	memcpy(guest_hv_clock, &hv_clock, sizeof(*guest_hv_clock));
+-	memcpy(guest_hv_clock, &vcpu->hv_clock, sizeof(*guest_hv_clock));
+-
+-	if (force_tsc_unstable)
+-		guest_hv_clock->flags &= ~PVCLOCK_TSC_STABLE_BIT;
 +	kvm_write_guest(vcpu->kvm, gpa, &hv_clock, sizeof(struct pvclock_vcpu_time_info));
 
  	smp_wmb();
 
--	guest_hv_clock->version = ++hv_clock.version;
+-	guest_hv_clock->version = ++vcpu->hv_clock.version;
 -
 -	kvm_gpc_mark_dirty_in_slot(gpc);
 -	read_unlock_irqrestore(&gpc->lock, flags);
 +	++hv_clock.version;
 +	kvm_write_guest(vcpu->kvm, gpa + offsetof(struct pvclock_vcpu_time_info, version), &hv_clock.version, sizeof(hv_clock.version));
 
- 	trace_kvm_pvclock_update(vcpu->vcpu_id, &hv_clock);
+-	trace_kvm_pvclock_update(v->vcpu_id, &vcpu->hv_clock);
++	trace_kvm_pvclock_update(vcpu->vcpu_id, &hv_clock);
  }
-@@ -3264,7 +3247,7 @@ int kvm_guest_time_update(struct kvm_vcpu *v)
- 	if (use_master_clock)
- 		hv_clock.flags |= PVCLOCK_TSC_STABLE_BIT;
 
--	if (vcpu->pv_time.active) {
+ static int kvm_guest_time_update(struct kvm_vcpu *v)
+@@ -3267,8 +3244,8 @@ static int kvm_guest_time_update(struct kvm_vcpu *v)
+ 
+ 	vcpu->hv_clock.flags = pvclock_flags;
+ 
+-	if (vcpu->pv_time.active)
+-		kvm_setup_guest_pvclock(v, &vcpu->pv_time, 0, false);
 +	if (vcpu->system_time != INVALID_GPA) {
- 		/*
- 		 * GUEST_STOPPED is only supported by kvmclock, and KVM's
- 		 * historic behavior is to only process the request if kvmclock
-@@ -3274,7 +3257,7 @@ int kvm_guest_time_update(struct kvm_vcpu *v)
- 			hv_clock.flags |= PVCLOCK_GUEST_STOPPED;
- 			vcpu->pvclock_set_guest_stopped_request = false;
- 		}
--		kvm_setup_guest_pvclock(&hv_clock, v, &vcpu->pv_time, 0);
-+		kvm_setup_guest_pvclock(&hv_clock, v, vcpu->system_time);
- 
- 		hv_clock.flags &= ~PVCLOCK_GUEST_STOPPED;
- 	}
-@@ -3590,7 +3573,7 @@ static int kvm_pv_enable_async_pf_int(struct kvm_vcpu *vcpu, u64 data)
++		kvm_setup_guest_pvclock(v, &vcpu->pv_time, vcpu->system_time);
+ #ifdef CONFIG_KVM_XEN
+ 	if (vcpu->xen.vcpu_info_cache.active)
+ 		kvm_setup_guest_pvclock(v, &vcpu->xen.vcpu_info_cache,
+@@ -3570,7 +3547,7 @@ static int kvm_pv_enable_async_pf_int(struct kvm_vcpu *vcpu, u64 data)
 
  static void kvmclock_reset(struct kvm_vcpu *vcpu)
  {
 -	kvm_gpc_deactivate(&vcpu->arch.pv_time);
-+	vcpu->arch.system_time = INVALID_GPA;
++	vcpu->arch.syste_time = INVALID_GPA;
  	vcpu->arch.time = 0;
  }
 
-@@ -5688,7 +5671,7 @@ static int kvm_vcpu_ioctl_x86_set_xcrs(struct kvm_vcpu *vcpu,
+@@ -5656,7 +5633,7 @@ static int kvm_vcpu_ioctl_x86_set_xcrs(struct kvm_vcpu *vcpu,
   */
  static int kvm_set_guest_paused(struct kvm_vcpu *vcpu)
  {
@@ -133,14 +141,14 @@ index 2a02f2457c42..5aad662ec0e1 100644
  		return -EINVAL;
  	vcpu->arch.pvclock_set_guest_stopped_request = true;
  	kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu);
-@@ -12278,8 +12261,6 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
+@@ -12251,8 +12228,6 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
  	vcpu->arch.regs_avail = ~0;
  	vcpu->arch.regs_dirty = ~0;
 
 -	kvm_gpc_init(&vcpu->arch.pv_time, vcpu->kvm);
 -
  	if (!irqchip_in_kernel(vcpu->kvm) || kvm_vcpu_is_reset_bsp(vcpu))
- 		kvm_set_mp_state(vcpu, KVM_MP_STATE_RUNNABLE);
+ 		vcpu->arch.mp_state = KVM_MP_STATE_RUNNABLE;
  	else
 -- 
 2.49.0