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Subject[PATCH 03/40] KVM: SVM: Add helper functions for nested SVM
Date
From: Alexander Graf <agraf@suse.de>

These are helpers for the nested SVM implementation.

- nsvm_printk implements a debug printk variant
- nested_svm_do calls a handler that can accesses gpa-based memory

v3 makes use of the new permission checker
v6 changes:
- streamline nsvm_debug()
- remove printk(KERN_ERR)
- SVME check before CPL check
- give GP error code
- use new EFER constant

Acked-by: Joerg Roedel <joro@8bytes.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Avi Kivity <avi@redhat.com>
---
arch/x86/kvm/svm.c | 85 ++++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 85 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index e4eb3fd..87debdc 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -50,6 +50,15 @@ MODULE_LICENSE("GPL");

#define DEBUGCTL_RESERVED_BITS (~(0x3fULL))

+/* Turn on to get debugging output*/
+/* #define NESTED_DEBUG */
+
+#ifdef NESTED_DEBUG
+#define nsvm_printk(fmt, args...) printk(KERN_INFO fmt, ## args)
+#else
+#define nsvm_printk(fmt, args...) do {} while(0)
+#endif
+
/* enable NPT for AMD64 and X86 with PAE */
#if defined(CONFIG_X86_64) || defined(CONFIG_X86_PAE)
static bool npt_enabled = true;
@@ -1149,6 +1158,82 @@ static int vmmcall_interception(struct vcpu_svm *svm, struct kvm_run *kvm_run)
return 1;
}

+static int nested_svm_check_permissions(struct vcpu_svm *svm)
+{
+ if (!(svm->vcpu.arch.shadow_efer & EFER_SVME)
+ || !is_paging(&svm->vcpu)) {
+ kvm_queue_exception(&svm->vcpu, UD_VECTOR);
+ return 1;
+ }
+
+ if (svm->vmcb->save.cpl) {
+ kvm_inject_gp(&svm->vcpu, 0);
+ return 1;
+ }
+
+ return 0;
+}
+
+static struct page *nested_svm_get_page(struct vcpu_svm *svm, u64 gpa)
+{
+ struct page *page;
+
+ down_read(&current->mm->mmap_sem);
+ page = gfn_to_page(svm->vcpu.kvm, gpa >> PAGE_SHIFT);
+ up_read(&current->mm->mmap_sem);
+
+ if (is_error_page(page)) {
+ printk(KERN_INFO "%s: could not find page at 0x%llx\n",
+ __func__, gpa);
+ kvm_release_page_clean(page);
+ kvm_inject_gp(&svm->vcpu, 0);
+ return NULL;
+ }
+ return page;
+}
+
+static int nested_svm_do(struct vcpu_svm *svm,
+ u64 arg1_gpa, u64 arg2_gpa, void *opaque,
+ int (*handler)(struct vcpu_svm *svm,
+ void *arg1,
+ void *arg2,
+ void *opaque))
+{
+ struct page *arg1_page;
+ struct page *arg2_page = NULL;
+ void *arg1;
+ void *arg2 = NULL;
+ int retval;
+
+ arg1_page = nested_svm_get_page(svm, arg1_gpa);
+ if(arg1_page == NULL)
+ return 1;
+
+ if (arg2_gpa) {
+ arg2_page = nested_svm_get_page(svm, arg2_gpa);
+ if(arg2_page == NULL) {
+ kvm_release_page_clean(arg1_page);
+ return 1;
+ }
+ }
+
+ arg1 = kmap_atomic(arg1_page, KM_USER0);
+ if (arg2_gpa)
+ arg2 = kmap_atomic(arg2_page, KM_USER1);
+
+ retval = handler(svm, arg1, arg2, opaque);
+
+ kunmap_atomic(arg1, KM_USER0);
+ if (arg2_gpa)
+ kunmap_atomic(arg2, KM_USER1);
+
+ kvm_release_page_dirty(arg1_page);
+ if (arg2_gpa)
+ kvm_release_page_dirty(arg2_page);
+
+ return retval;
+}
+
static int invalid_op_interception(struct vcpu_svm *svm,
struct kvm_run *kvm_run)
{
--
1.6.0.6


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