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Message-Id: <1508224209-15366-4-git-send-email-eric.auger@redhat.com>
Date: Tue, 17 Oct 2017 09:10:01 +0200
From: Eric Auger <eric.auger@...hat.com>
To: eric.auger.pro@...il.com, eric.auger@...hat.com,
linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
kvmarm@...ts.cs.columbia.edu, marc.zyngier@....com,
cdall@...aro.org, peter.maydell@...aro.org, andre.przywara@....com,
wanghaibin.wang@...wei.com
Cc: wu.wubin@...wei.com, drjones@...hat.com, wei@...hat.com
Subject: [PATCH v4 03/11] KVM: arm/arm64: vgic-its: Improve error reporting on device table save
At the moment the device table save() returns -EINVAL if
vgic_its_check_id() fails to return the gpa of the entry
associated to the device/collection id. Let vgic_its_check_id()
return an int instead of a bool and return a more precised
error value:
- EINVAL in case the id is out of range
- EFAULT if the gpa is not provisionned or is not valid
We also check first the GITS_BASER<n> Valid bit is set.
This allows the userspace to discriminate failure reasons.
Signed-off-by: Eric Auger <eric.auger@...hat.com>
---
need to CC stable
v2 -> v3:
- correct kerneldoc comment
---
virt/kvm/arm/vgic/vgic-its.c | 55 +++++++++++++++++++++++++++++---------------
1 file changed, 37 insertions(+), 18 deletions(-)
diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
index a4ff8f7..e59363e 100644
--- a/virt/kvm/arm/vgic/vgic-its.c
+++ b/virt/kvm/arm/vgic/vgic-its.c
@@ -687,15 +687,25 @@ static int vgic_its_cmd_handle_movi(struct kvm *kvm, struct vgic_its *its,
return 0;
}
-/*
- * Check whether an ID can be stored into the corresponding guest table.
+/**
+ * vgic_its_check_id - Check whether an ID can be stored into
+ * the corresponding guest table.
+ *
+ * @its: its handle
+ * @baser: GITS_BASER<n> register
+ * @id: id of the device/collection
+ * @eaddr: output gpa of the corresponding table entry
+ *
* For a direct table this is pretty easy, but gets a bit nasty for
* indirect tables. We check whether the resulting guest physical address
* is actually valid (covered by a memslot and guest accessible).
* For this we have to read the respective first level entry.
+ *
+ * Return: 0 on success, -EINVAL if @id is out of range, -EFAULT if
+ * the address cannot be computed or is not valid
*/
-static bool vgic_its_check_id(struct vgic_its *its, u64 baser, u32 id,
- gpa_t *eaddr)
+static int vgic_its_check_id(struct vgic_its *its, u64 baser, u32 id,
+ gpa_t *eaddr)
{
int l1_tbl_size = GITS_BASER_NR_PAGES(baser) * SZ_64K;
u64 indirect_ptr, type = GITS_BASER_TYPE(baser);
@@ -703,50 +713,56 @@ static bool vgic_its_check_id(struct vgic_its *its, u64 baser, u32 id,
int index;
gfn_t gfn;
+ if (!(baser & GITS_BASER_VALID))
+ return -EFAULT;
+
switch (type) {
case GITS_BASER_TYPE_DEVICE:
if (id >= BIT_ULL(VITS_TYPER_DEVBITS))
- return false;
+ return -EINVAL;
break;
case GITS_BASER_TYPE_COLLECTION:
/* as GITS_TYPER.CIL == 0, ITS supports 16-bit collection ID */
if (id >= BIT_ULL(16))
- return false;
+ return -EINVAL;
break;
default:
- return false;
+ return -EINVAL;
}
if (!(baser & GITS_BASER_INDIRECT)) {
phys_addr_t addr;
if (id >= (l1_tbl_size / esz))
- return false;
+ return -EINVAL;
addr = BASER_ADDRESS(baser) + id * esz;
gfn = addr >> PAGE_SHIFT;
if (eaddr)
*eaddr = addr;
- return kvm_is_visible_gfn(its->dev->kvm, gfn);
+ if (kvm_is_visible_gfn(its->dev->kvm, gfn))
+ return 0;
+ else
+ return -EFAULT;
}
/* calculate and check the index into the 1st level */
index = id / (SZ_64K / esz);
if (index >= (l1_tbl_size / sizeof(u64)))
- return false;
+ return -EINVAL;
/* Each 1st level entry is represented by a 64-bit value. */
if (kvm_read_guest(its->dev->kvm,
BASER_ADDRESS(baser) + index * sizeof(indirect_ptr),
&indirect_ptr, sizeof(indirect_ptr)))
- return false;
+ return -EFAULT;
indirect_ptr = le64_to_cpu(indirect_ptr);
/* check the valid bit of the first level entry */
if (!(indirect_ptr & BIT_ULL(63)))
- return false;
+ return -EFAULT;
/*
* Mask the guest physical address and calculate the frame number.
@@ -762,7 +778,10 @@ static bool vgic_its_check_id(struct vgic_its *its, u64 baser, u32 id,
if (eaddr)
*eaddr = indirect_ptr;
- return kvm_is_visible_gfn(its->dev->kvm, gfn);
+ if (kvm_is_visible_gfn(its->dev->kvm, gfn))
+ return 0;
+ else
+ return -EFAULT;
}
static int vgic_its_alloc_collection(struct vgic_its *its,
@@ -771,7 +790,7 @@ static int vgic_its_alloc_collection(struct vgic_its *its,
{
struct its_collection *collection;
- if (!vgic_its_check_id(its, its->baser_coll_table, coll_id, NULL))
+ if (vgic_its_check_id(its, its->baser_coll_table, coll_id, NULL))
return E_ITS_MAPC_COLLECTION_OOR;
collection = kzalloc(sizeof(*collection), GFP_KERNEL);
@@ -943,7 +962,7 @@ static int vgic_its_cmd_handle_mapd(struct kvm *kvm, struct vgic_its *its,
gpa_t itt_addr = its_cmd_get_ittaddr(its_cmd);
struct its_device *device;
- if (!vgic_its_check_id(its, its->baser_device_table, device_id, NULL))
+ if (vgic_its_check_id(its, its->baser_device_table, device_id, NULL))
return E_ITS_MAPD_DEVICE_OOR;
if (valid && num_eventid_bits > VITS_TYPER_IDBITS)
@@ -2093,9 +2112,9 @@ static int vgic_its_save_device_tables(struct vgic_its *its)
int ret;
gpa_t eaddr;
- if (!vgic_its_check_id(its, baser,
- dev->device_id, &eaddr))
- return -EINVAL;
+ ret = vgic_its_check_id(its, baser, dev->device_id, &eaddr);
+ if (ret)
+ return ret;
ret = vgic_its_save_itt(its, dev);
if (ret)
--
2.5.5
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