drm/i915/gvt/kvmgt: read/write GPA via KVM API
Previously to read/write a GPA, we at first try to pin the GFN it belongs
to, then translate the pinned PFN to a kernel HVA, then read/write it.
This is however not necessary. A GFN should be pinned IFF it would be
accessed by peripheral devices (DMA), not by CPU. This patch changes
the read/write method to KVM API, which will leverage userspace HVA
and copy_{from|to}_usr instead.
Signed-off-by: Jike Song <jike.song@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c b/drivers/gpu/drm/i915/gvt/kvmgt.c
index aecb657..24496ad 100644
--- a/drivers/gpu/drm/i915/gvt/kvmgt.c
+++ b/drivers/gpu/drm/i915/gvt/kvmgt.c
@@ -31,6 +31,7 @@
#include <linux/init.h>
#include <linux/device.h>
#include <linux/mm.h>
+#include <linux/mmu_context.h>
#include <linux/types.h>
#include <linux/list.h>
#include <linux/rbtree.h>
@@ -519,33 +520,27 @@
return pfn;
}
-static void *kvmgt_gpa_to_hva(unsigned long handle, unsigned long gpa)
-{
- unsigned long pfn;
- gfn_t gfn = gpa_to_gfn(gpa);
-
- pfn = kvmgt_gfn_to_pfn(handle, gfn);
- if (!pfn)
- return NULL;
-
- return (char *)pfn_to_kaddr(pfn) + offset_in_page(gpa);
-}
-
static int kvmgt_rw_gpa(unsigned long handle, unsigned long gpa,
void *buf, unsigned long len, bool write)
{
- void *hva = NULL;
+ struct kvmgt_guest_info *info;
+ struct kvm *kvm;
+ int ret;
+ bool kthread = current->mm == NULL;
- hva = kvmgt_gpa_to_hva(handle, gpa);
- if (!hva)
- return -EFAULT;
+ info = (struct kvmgt_guest_info *)handle;
+ kvm = info->kvm;
- if (write)
- memcpy(hva, buf, len);
- else
- memcpy(buf, hva, len);
+ if (kthread)
+ use_mm(kvm->mm);
- return 0;
+ ret = write ? kvm_write_guest(kvm, gpa, buf, len) :
+ kvm_read_guest(kvm, gpa, buf, len);
+
+ if (kthread)
+ unuse_mm(kvm->mm);
+
+ return ret;
}
static int kvmgt_read_gpa(unsigned long handle, unsigned long gpa,