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From: Claudio Imbrenda <imbrenda@linux.ibm.com>
To: kvm@vger.kernel.org
Cc: cohuck@redhat.com, borntraeger@de.ibm.com, frankja@linux.ibm.com,
	thuth@redhat.com, pasic@linux.ibm.com, david@redhat.com,
	linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH v2 03/13] KVM: s390: pv: properly handle page flags for protected guests
Date: Wed, 28 Jul 2021 16:26:21 +0200	[thread overview]
Message-ID: <20210728142631.41860-4-imbrenda@linux.ibm.com> (raw)
In-Reply-To: <20210728142631.41860-1-imbrenda@linux.ibm.com>

Introduce variants of the convert and destroy page functions that also
clear the PG_arch_1 bit used to mark them as secure pages.

These new functions can only be called on pages for which a reference
is already being held.

Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
---
 arch/s390/include/asm/pgtable.h |  9 ++++++---
 arch/s390/include/asm/uv.h      | 10 ++++++++--
 arch/s390/kernel/uv.c           | 34 ++++++++++++++++++++++++++++++++-
 arch/s390/mm/gmap.c             |  4 +++-
 4 files changed, 50 insertions(+), 7 deletions(-)

diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h
index dcac7b2df72c..0f1af2232ebe 100644
--- a/arch/s390/include/asm/pgtable.h
+++ b/arch/s390/include/asm/pgtable.h
@@ -1074,8 +1074,9 @@ static inline pte_t ptep_get_and_clear(struct mm_struct *mm,
 	pte_t res;
 
 	res = ptep_xchg_lazy(mm, addr, ptep, __pte(_PAGE_INVALID));
+	/* At this point the reference through the mapping is still present */
 	if (mm_is_protected(mm) && pte_present(res))
-		uv_convert_from_secure(pte_val(res) & PAGE_MASK);
+		uv_convert_owned_from_secure(pte_val(res) & PAGE_MASK);
 	return res;
 }
 
@@ -1091,8 +1092,9 @@ static inline pte_t ptep_clear_flush(struct vm_area_struct *vma,
 	pte_t res;
 
 	res = ptep_xchg_direct(vma->vm_mm, addr, ptep, __pte(_PAGE_INVALID));
+	/* At this point the reference through the mapping is still present */
 	if (mm_is_protected(vma->vm_mm) && pte_present(res))
-		uv_convert_from_secure(pte_val(res) & PAGE_MASK);
+		uv_convert_owned_from_secure(pte_val(res) & PAGE_MASK);
 	return res;
 }
 
@@ -1116,8 +1118,9 @@ static inline pte_t ptep_get_and_clear_full(struct mm_struct *mm,
 	} else {
 		res = ptep_xchg_lazy(mm, addr, ptep, __pte(_PAGE_INVALID));
 	}
+	/* At this point the reference through the mapping is still present */
 	if (mm_is_protected(mm) && pte_present(res))
-		uv_convert_from_secure(pte_val(res) & PAGE_MASK);
+		uv_convert_owned_from_secure(pte_val(res) & PAGE_MASK);
 	return res;
 }
 
diff --git a/arch/s390/include/asm/uv.h b/arch/s390/include/asm/uv.h
index 12c5f006c136..bbd51aa94d05 100644
--- a/arch/s390/include/asm/uv.h
+++ b/arch/s390/include/asm/uv.h
@@ -351,8 +351,9 @@ static inline int is_prot_virt_host(void)
 }
 
 int gmap_make_secure(struct gmap *gmap, unsigned long gaddr, void *uvcb);
-int uv_destroy_page(unsigned long paddr);
+int uv_destroy_owned_page(unsigned long paddr);
 int uv_convert_from_secure(unsigned long paddr);
+int uv_convert_owned_from_secure(unsigned long paddr);
 int gmap_convert_to_secure(struct gmap *gmap, unsigned long gaddr);
 
 void setup_uv(void);
@@ -362,7 +363,7 @@ void adjust_to_uv_max(unsigned long *vmax);
 static inline void setup_uv(void) {}
 static inline void adjust_to_uv_max(unsigned long *vmax) {}
 
-static inline int uv_destroy_page(unsigned long paddr)
+static inline int uv_destroy_owned_page(unsigned long paddr)
 {
 	return 0;
 }
@@ -371,6 +372,11 @@ static inline int uv_convert_from_secure(unsigned long paddr)
 {
 	return 0;
 }
+
+static inline int uv_convert_owned_from_secure(unsigned long paddr)
+{
+	return 0;
+}
 #endif
 
 #if defined(CONFIG_PROTECTED_VIRTUALIZATION_GUEST) || IS_ENABLED(CONFIG_KVM)
diff --git a/arch/s390/kernel/uv.c b/arch/s390/kernel/uv.c
index fd0faa51c1bb..5a6ac965f379 100644
--- a/arch/s390/kernel/uv.c
+++ b/arch/s390/kernel/uv.c
@@ -115,7 +115,7 @@ static int uv_pin_shared(unsigned long paddr)
  *
  * @paddr: Absolute host address of page to be destroyed
  */
-int uv_destroy_page(unsigned long paddr)
+static int uv_destroy_page(unsigned long paddr)
 {
 	struct uv_cb_cfs uvcb = {
 		.header.cmd = UVC_CMD_DESTR_SEC_STOR,
@@ -135,6 +135,22 @@ int uv_destroy_page(unsigned long paddr)
 	return 0;
 }
 
+/*
+ * The caller must already hold a reference to the page
+ */
+int uv_destroy_owned_page(unsigned long paddr)
+{
+	struct page *page = phys_to_page(paddr);
+	int rc;
+
+	get_page(page);
+	rc = uv_destroy_page(paddr);
+	if (!rc)
+		clear_bit(PG_arch_1, &page->flags);
+	put_page(page);
+	return rc;
+}
+
 /*
  * Requests the Ultravisor to encrypt a guest page and make it
  * accessible to the host for paging (export).
@@ -154,6 +170,22 @@ int uv_convert_from_secure(unsigned long paddr)
 	return 0;
 }
 
+/*
+ * The caller must already hold a reference to the page
+ */
+int uv_convert_owned_from_secure(unsigned long paddr)
+{
+	struct page *page = phys_to_page(paddr);
+	int rc;
+
+	get_page(page);
+	rc = uv_convert_from_secure(paddr);
+	if (!rc)
+		clear_bit(PG_arch_1, &page->flags);
+	put_page(page);
+	return rc;
+}
+
 /*
  * Calculate the expected ref_count for a page that would otherwise have no
  * further pins. This was cribbed from similar functions in other places in
diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c
index 9bb2c7512cd5..de679facc720 100644
--- a/arch/s390/mm/gmap.c
+++ b/arch/s390/mm/gmap.c
@@ -2678,8 +2678,10 @@ static int __s390_reset_acc(pte_t *ptep, unsigned long addr,
 {
 	pte_t pte = READ_ONCE(*ptep);
 
+	/* There is a reference through the mapping */
 	if (pte_present(pte))
-		WARN_ON_ONCE(uv_destroy_page(pte_val(pte) & PAGE_MASK));
+		WARN_ON_ONCE(uv_destroy_owned_page(pte_val(pte) & PAGE_MASK));
+
 	return 0;
 }
 
-- 
2.31.1


  parent reply	other threads:[~2021-07-28 14:31 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-28 14:26 [PATCH v2 00/13] KVM: s390: pv: implement lazy destroy Claudio Imbrenda
2021-07-28 14:26 ` [PATCH v2 01/13] KVM: s390: pv: avoid stall notifications for some UVCs Claudio Imbrenda
2021-07-29  9:58   ` Janosch Frank
2021-07-29 12:52     ` Claudio Imbrenda
2021-07-29 10:49   ` Cornelia Huck
2021-07-29 13:22     ` Claudio Imbrenda
2021-07-28 14:26 ` [PATCH v2 02/13] KVM: s390: pv: leak the ASCE page when destroy fails Claudio Imbrenda
2021-07-29 10:41   ` Janosch Frank
2021-07-29 12:54     ` Claudio Imbrenda
2021-07-29 13:45       ` Janosch Frank
2021-07-28 14:26 ` Claudio Imbrenda [this message]
2021-07-29 11:43   ` [PATCH v2 03/13] KVM: s390: pv: properly handle page flags for protected guests Janosch Frank
2021-07-28 14:26 ` [PATCH v2 04/13] KVM: s390: pv: handle secure storage violations " Claudio Imbrenda
2021-07-28 14:26 ` [PATCH v2 05/13] KVM: s390: pv: handle secure storage exceptions for normal guests Claudio Imbrenda
2021-07-29 12:17   ` Janosch Frank
2021-07-29 13:28     ` Claudio Imbrenda
2021-07-28 14:26 ` [PATCH v2 06/13] KVM: s390: pv: refactor s390_reset_acc Claudio Imbrenda
2021-07-28 14:26 ` [PATCH v2 07/13] KVM: s390: pv: usage counter instead of flag Claudio Imbrenda
2021-07-28 14:26 ` [PATCH v2 08/13] KVM: s390: pv: add export before import Claudio Imbrenda
2021-07-28 14:26 ` [PATCH v2 09/13] KVM: s390: pv: lazy destroy for reboot Claudio Imbrenda
2021-07-28 14:26 ` [PATCH v2 10/13] KVM: s390: pv: extend lazy destroy to handle shutdown Claudio Imbrenda
2021-07-28 14:26 ` [PATCH v2 11/13] KVM: s390: pv: module parameter to fence lazy destroy Claudio Imbrenda
2021-07-28 14:26 ` [PATCH v2 12/13] KVM: s390: pv: add OOM notifier for " Claudio Imbrenda
2021-07-28 14:26 ` [PATCH v2 13/13] KVM: s390: pv: add support for UV feature bits Claudio Imbrenda
2021-07-29  9:52   ` Janosch Frank
2021-07-29 13:28     ` Claudio Imbrenda

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