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From: Alexandre Chartre <alexandre.chartre@oracle.com>
To: pbonzini@redhat.com, rkrcmar@redhat.com, tglx@linutronix.de,
	mingo@redhat.com, bp@alien8.de, hpa@zytor.com,
	dave.hansen@linux.intel.com, luto@kernel.org,
	peterz@infradead.org, kvm@vger.kernel.org, x86@kernel.org,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org
Cc: konrad.wilk@oracle.com, jan.setjeeilers@oracle.com,
	liran.alon@oracle.com, jwadams@google.com,
	alexandre.chartre@oracle.com
Subject: [RFC KVM 13/27] kvm/isolation: add KVM page table entry set functions
Date: Mon, 13 May 2019 16:38:21 +0200	[thread overview]
Message-ID: <1557758315-12667-14-git-send-email-alexandre.chartre@oracle.com> (raw)
In-Reply-To: <1557758315-12667-1-git-send-email-alexandre.chartre@oracle.com>

Add wrappers around the page table entry (pgd/p4d/pud/pmd) set function
to check that an existing entry is not being overwritten.

Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com>
---
 arch/x86/kvm/isolation.c |  107 ++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 107 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kvm/isolation.c b/arch/x86/kvm/isolation.c
index 6ec86df..b681e4f 100644
--- a/arch/x86/kvm/isolation.c
+++ b/arch/x86/kvm/isolation.c
@@ -342,6 +342,113 @@ static inline void kvm_p4d_free(struct mm_struct *mm, p4d_t *p4d)
 	return p4d;
 }
 
+/*
+ * kvm_set_pXX() functions are equivalent to kernel set_pXX() functions
+ * but, in addition, they ensure that they are not overwriting an already
+ * existing reference in the page table. Otherwise an error is returned.
+ *
+ * Note that this is not used for PTE because a PTE entry points to page
+ * frames containing the actual user data, and not to another entry in the
+ * page table. However this is used for PGD.
+ */
+
+static int kvm_set_pmd(pmd_t *pmd, pmd_t pmd_value)
+{
+#ifdef DEBUG
+	/*
+	 * The pmd pointer should come from kvm_pmd_alloc() or kvm_pmd_offset()
+	 * both of which check if the pointer is in the KVM page table. So this
+	 * is a paranoid check to ensure the pointer is really in the KVM page
+	 * table.
+	 */
+	if (!kvm_valid_pgt_entry(pmd)) {
+		pr_err("PMD %px is not in KVM page table\n", pmd);
+		return -EINVAL;
+	}
+#endif
+	if (pmd_val(*pmd) == pmd_val(pmd_value))
+		return 0;
+
+	if (!pmd_none(*pmd)) {
+		pr_err("PMD %px: overwriting %lx with %lx\n",
+		    pmd, pmd_val(*pmd), pmd_val(pmd_value));
+		return -EBUSY;
+	}
+
+	set_pmd(pmd, pmd_value);
+
+	return 0;
+}
+
+static int kvm_set_pud(pud_t *pud, pud_t pud_value)
+{
+#ifdef DEBUG
+	/*
+	 * The pud pointer should come from kvm_pud_alloc() or kvm_pud_offset()
+	 * both of which check if the pointer is in the KVM page table. So this
+	 * is a paranoid check to ensure the pointer is really in the KVM page
+	 * table.
+	 */
+	if (!kvm_valid_pgt_entry(pud)) {
+		pr_err("PUD %px is not in KVM page table\n", pud);
+		return -EINVAL;
+	}
+#endif
+	if (pud_val(*pud) == pud_val(pud_value))
+		return 0;
+
+	if (!pud_none(*pud)) {
+		pr_err("PUD %px: overwriting %lx\n", pud, pud_val(*pud));
+		return -EBUSY;
+	}
+
+	set_pud(pud, pud_value);
+
+	return 0;
+}
+
+static int kvm_set_p4d(p4d_t *p4d, p4d_t p4d_value)
+{
+#ifdef DEBUG
+	/*
+	 * The p4d pointer should come from kvm_p4d_alloc() or kvm_p4d_offset()
+	 * both of which check if the pointer is in the KVM page table. So this
+	 * is a paranoid check to ensure the pointer is really in the KVM page
+	 * table.
+	 */
+	if (!kvm_valid_pgt_entry(p4d)) {
+		pr_err("P4D %px is not in KVM page table\n", p4d);
+		return -EINVAL;
+	}
+#endif
+	if (p4d_val(*p4d) == p4d_val(p4d_value))
+		return 0;
+
+	if (!p4d_none(*p4d)) {
+		pr_err("P4D %px: overwriting %lx\n", p4d, p4d_val(*p4d));
+		return -EBUSY;
+	}
+
+	set_p4d(p4d, p4d_value);
+
+	return 0;
+}
+
+static int kvm_set_pgd(pgd_t *pgd, pgd_t pgd_value)
+{
+	if (pgd_val(*pgd) == pgd_val(pgd_value))
+		return 0;
+
+	if (!pgd_none(*pgd)) {
+		pr_err("PGD %px: overwriting %lx\n", pgd, pgd_val(*pgd));
+		return -EBUSY;
+	}
+
+	set_pgd(pgd, pgd_value);
+
+	return 0;
+}
+
 
 static int kvm_isolation_init_mm(void)
 {
-- 
1.7.1


  parent reply	other threads:[~2019-05-13 14:40 UTC|newest]

Thread overview: 86+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-13 14:38 [RFC KVM 00/27] KVM Address Space Isolation Alexandre Chartre
2019-05-13 14:38 ` [RFC KVM 01/27] kernel: Export memory-management symbols required for KVM address space isolation Alexandre Chartre
2019-05-13 15:15   ` Peter Zijlstra
2019-05-13 15:17     ` Liran Alon
2019-05-13 14:38 ` [RFC KVM 02/27] KVM: x86: Introduce address_space_isolation module parameter Alexandre Chartre
2019-05-13 15:46   ` Andy Lutomirski
2019-05-13 15:55     ` Alexandre Chartre
2019-05-13 14:38 ` [RFC KVM 03/27] KVM: x86: Introduce KVM separate virtual address space Alexandre Chartre
2019-05-13 15:45   ` Andy Lutomirski
2019-05-13 16:04     ` Alexandre Chartre
2019-05-13 14:38 ` [RFC KVM 04/27] KVM: x86: Switch to KVM address space on entry to guest Alexandre Chartre
2019-05-13 14:38 ` [RFC KVM 05/27] KVM: x86: Add handler to exit kvm isolation Alexandre Chartre
2019-05-13 15:49   ` Andy Lutomirski
2019-05-13 16:10     ` Alexandre Chartre
2019-05-13 14:38 ` [RFC KVM 06/27] KVM: x86: Exit KVM isolation on IRQ entry Alexandre Chartre
2019-05-13 15:51   ` Andy Lutomirski
2019-05-13 16:28     ` Alexandre Chartre
2019-05-13 18:13       ` Andy Lutomirski
2019-05-14  7:07         ` Peter Zijlstra
2019-05-14  7:58           ` Alexandre Chartre
2019-05-13 14:38 ` [RFC KVM 07/27] KVM: x86: Switch to host address space when may access sensitive data Alexandre Chartre
2019-05-13 14:38 ` [RFC KVM 08/27] KVM: x86: Optimize branches which checks if address space isolation enabled Alexandre Chartre
2019-05-13 14:38 ` [RFC KVM 09/27] kvm/isolation: function to track buffers allocated for the KVM page table Alexandre Chartre
2019-05-13 14:38 ` [RFC KVM 10/27] kvm/isolation: add KVM page table entry free functions Alexandre Chartre
2019-05-13 14:38 ` [RFC KVM 11/27] kvm/isolation: add KVM page table entry offset functions Alexandre Chartre
2019-05-13 14:38 ` [RFC KVM 12/27] kvm/isolation: add KVM page table entry allocation functions Alexandre Chartre
2019-05-13 14:38 ` Alexandre Chartre [this message]
2019-05-13 14:38 ` [RFC KVM 14/27] kvm/isolation: functions to copy page table entries for a VA range Alexandre Chartre
2019-05-13 14:38 ` [RFC KVM 15/27] kvm/isolation: keep track of VA range mapped in KVM address space Alexandre Chartre
2019-05-13 14:38 ` [RFC KVM 16/27] kvm/isolation: functions to clear page table entries for a VA range Alexandre Chartre
2019-05-13 14:38 ` [RFC KVM 17/27] kvm/isolation: improve mapping copy when mapping is already present Alexandre Chartre
2019-05-13 14:38 ` [RFC KVM 18/27] kvm/isolation: function to copy page table entries for percpu buffer Alexandre Chartre
2019-05-13 18:18   ` Andy Lutomirski
2019-05-14  7:09     ` Peter Zijlstra
2019-05-14  8:25       ` Alexandre Chartre
2019-05-14  8:34         ` Andy Lutomirski
2019-05-14  9:41           ` Alexandre Chartre
2019-05-14 15:23             ` Andy Lutomirski
2019-05-14 16:24               ` Alexandre Chartre
2019-05-14 17:05                 ` Peter Zijlstra
2019-05-14 18:09                   ` Sean Christopherson
2019-05-14 20:33                     ` Andy Lutomirski
2019-05-14 21:06                       ` Sean Christopherson
2019-05-14 21:55                         ` Andy Lutomirski
2019-05-14 22:38                           ` Sean Christopherson
2019-05-18  0:05                             ` Jonathan Adams
2019-05-14 20:27                   ` Andy Lutomirski
2019-05-13 14:38 ` [RFC KVM 19/27] kvm/isolation: initialize the KVM page table with core mappings Alexandre Chartre
2019-05-13 15:50   ` Dave Hansen
2019-05-13 16:00     ` Andy Lutomirski
2019-05-13 17:00       ` Alexandre Chartre
2019-05-13 16:46     ` Sean Christopherson
2019-05-13 16:47     ` Alexandre Chartre
2019-05-14 10:26       ` Alexandre Chartre
2019-05-13 14:38 ` [RFC KVM 20/27] kvm/isolation: initialize the KVM page table with vmx specific data Alexandre Chartre
2019-05-13 14:38 ` [RFC KVM 21/27] kvm/isolation: initialize the KVM page table with vmx VM data Alexandre Chartre
2019-05-13 14:38 ` [RFC KVM 22/27] kvm/isolation: initialize the KVM page table with vmx cpu data Alexandre Chartre
2019-05-13 14:38 ` [RFC KVM 23/27] kvm/isolation: initialize the KVM page table with the vcpu tasks Alexandre Chartre
2019-05-13 14:38 ` [RFC KVM 24/27] kvm/isolation: KVM page fault handler Alexandre Chartre
2019-05-13 15:15   ` Peter Zijlstra
2019-05-13 21:25     ` Liran Alon
2019-05-14  2:02       ` Andy Lutomirski
2019-05-14  7:21         ` Peter Zijlstra
2019-05-14 15:36           ` Alexandre Chartre
2019-05-14 15:43             ` Andy Lutomirski
2019-05-13 16:02   ` Andy Lutomirski
2019-05-13 16:21     ` Alexandre Chartre
2019-05-13 14:38 ` [RFC KVM 25/27] kvm/isolation: implement actual KVM isolation enter/exit Alexandre Chartre
2019-05-13 15:16   ` Peter Zijlstra
2019-05-13 16:01   ` Andy Lutomirski
2019-05-13 14:38 ` [RFC KVM 26/27] kvm/isolation: initialize the KVM page table with KVM memslots Alexandre Chartre
2019-05-13 14:38 ` [RFC KVM 27/27] kvm/isolation: initialize the KVM page table with KVM buses Alexandre Chartre
2019-05-13 16:42 ` [RFC KVM 00/27] KVM Address Space Isolation Liran Alon
2019-05-13 18:17 ` Andy Lutomirski
2019-05-13 21:08   ` Liran Alon
2019-05-14  2:07     ` Andy Lutomirski
2019-05-14  7:37       ` Peter Zijlstra
2019-05-14 21:32         ` Jan Setje-Eilers
2019-05-14  8:05       ` Liran Alon
2019-05-14  7:29     ` Peter Zijlstra
2019-05-14  7:57       ` Liran Alon
2019-05-14  8:33     ` Alexandre Chartre
2019-05-13 19:31 ` Nakajima, Jun
2019-05-13 21:16   ` Liran Alon
     [not found]     ` <D07C8F51-F2DF-4C8B-AB3B-0DFABD5F4C33@intel.com>
2019-05-13 21:53       ` Liran Alon
2019-05-15 12:52 ` Alexandre Chartre

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