[PATCH v5 2/3] x86/altp2m: Add a hvmop for setting the suppress #VE bit

[Adrian Pop <apop@bitdefender.com>]

Introduce a new hvmop, HVMOP_altp2m_set_suppress_ve, which allows a
domain to change the value of the #VE suppress bit for a page.

Add a libxc wrapper for invoking this hvmop.

Signed-off-by: Adrian Pop <apop@bitdefender.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Acked-by: Tamas K Lengyel <tamas@tklengyel.com>
---
Changes in v5:
- remove the "set_" from struct xen_hvm_altp2m_set_suppress_ve

Changes in v4:
- fix a deadlock:
    If p2m_set_suppress_ve() is called on invalid pages the code path
    wrongly returns without releasing the lock, resulting in a deadlock.
- remove the privileged domain check

Changes in v3:
- fix indentation (Wei Liu)
- use return values other than EINVAL where appropriate (Ian Beulich)
- remove the irrelevant comments from the
  xen_hvm_altp2m_set_suppress_ve struct (Ian Beulich)
- add comment for the suppress_ve field in the struct above (Ian
  Beulich)
- remove the typedef and DEFINE_XEN_GUEST_HANDLE for
  xen_hvm_altp2m_set_suppress_ve (Ian Beulich)
- use XSM_DM_PRIV check instead of domain->is_privileged (Ian Beulich)

Changes in v2:
- check if #VE has been enabled on the target domain (Tamas K Lengyel)
- check if the cpu has the #VE feature
- make the suppress_ve argument boolean (Jan Beulich)
- initialize only local variables that need initializing (Jan Beulich)
- use fewer local variables (Jan Beulich)
- fix indentation (Jan Beulich)
- remove unnecessary braces (Jan Beulich)
- use gfn_lock() instead of p2m_lock() in the non-altp2m case (Jan
  Beulich)
- merge patch #2 and patch #3 (Jan Beulich)
---
 tools/libxc/include/xenctrl.h   |  2 ++
 tools/libxc/xc_altp2m.c         | 24 ++++++++++++++
 xen/arch/x86/hvm/hvm.c          | 14 +++++++++
 xen/arch/x86/mm/mem_access.c    | 55 +++++++++++++++++++++++++++++++++
 xen/include/public/hvm/hvm_op.h | 11 +++++++
 xen/include/xen/mem_access.h    |  3 ++
 6 files changed, 109 insertions(+)

diff --git a/tools/libxc/include/xenctrl.h b/tools/libxc/include/xenctrl.h
index c626984aba..cc8b3e7dce 100644
--- a/tools/libxc/include/xenctrl.h
+++ b/tools/libxc/include/xenctrl.h
@@ -1952,6 +1952,8 @@ int xc_altp2m_destroy_view(xc_interface *handle, uint32_t domid,
 /* Switch all vCPUs of the domain to the specified altp2m view */
 int xc_altp2m_switch_to_view(xc_interface *handle, uint32_t domid,
                              uint16_t view_id);
+int xc_altp2m_set_suppress_ve(xc_interface *handle, uint32_t domid,
+                              uint16_t view_id, xen_pfn_t gfn, bool sve);
 int xc_altp2m_set_mem_access(xc_interface *handle, uint32_t domid,
                              uint16_t view_id, xen_pfn_t gfn,
                              xenmem_access_t access);
diff --git a/tools/libxc/xc_altp2m.c b/tools/libxc/xc_altp2m.c
index ce4a1e4d60..f883d0b392 100644
--- a/tools/libxc/xc_altp2m.c
+++ b/tools/libxc/xc_altp2m.c
@@ -163,6 +163,30 @@ int xc_altp2m_switch_to_view(xc_interface *handle, uint32_t domid,
     return rc;
 }
 
+int xc_altp2m_set_suppress_ve(xc_interface *handle, uint32_t domid,
+                              uint16_t view_id, xen_pfn_t gfn, bool sve)
+{
+    int rc;
+    DECLARE_HYPERCALL_BUFFER(xen_hvm_altp2m_op_t, arg);
+
+    arg = xc_hypercall_buffer_alloc(handle, arg, sizeof(*arg));
+    if ( arg == NULL )
+        return -1;
+
+    arg->version = HVMOP_ALTP2M_INTERFACE_VERSION;
+    arg->cmd = HVMOP_altp2m_set_suppress_ve;
+    arg->domain = domid;
+    arg->u.suppress_ve.view = view_id;
+    arg->u.suppress_ve.gfn = gfn;
+    arg->u.suppress_ve.suppress_ve = sve;
+
+    rc = xencall2(handle->xcall, __HYPERVISOR_hvm_op, HVMOP_altp2m,
+                  HYPERCALL_BUFFER_AS_ARG(arg));
+
+    xc_hypercall_buffer_free(handle, arg);
+    return rc;
+}
+
 int xc_altp2m_set_mem_access(xc_interface *handle, uint32_t domid,
                              uint16_t view_id, xen_pfn_t gfn,
                              xenmem_access_t access)
diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index 72c51faecb..64ab36ff53 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -4524,6 +4524,7 @@ static int do_altp2m_op(
     case HVMOP_altp2m_create_p2m:
     case HVMOP_altp2m_destroy_p2m:
     case HVMOP_altp2m_switch_p2m:
+    case HVMOP_altp2m_set_suppress_ve:
     case HVMOP_altp2m_set_mem_access:
     case HVMOP_altp2m_set_mem_access_multi:
     case HVMOP_altp2m_change_gfn:
@@ -4641,6 +4642,19 @@ static int do_altp2m_op(
         rc = p2m_switch_domain_altp2m_by_id(d, a.u.view.view);
         break;
 
+    case HVMOP_altp2m_set_suppress_ve:
+        if ( a.u.suppress_ve.pad1 || a.u.suppress_ve.pad2 )
+            rc = -EINVAL;
+        else
+        {
+            gfn_t gfn = _gfn(a.u.set_mem_access.gfn);
+            unsigned int altp2m_idx = a.u.set_mem_access.view;
+            bool suppress_ve = a.u.suppress_ve.suppress_ve;
+
+            rc = p2m_set_suppress_ve(d, gfn, suppress_ve, altp2m_idx);
+        }
+        break;
+
     case HVMOP_altp2m_set_mem_access:
         if ( a.u.set_mem_access.pad )
             rc = -EINVAL;
diff --git a/xen/arch/x86/mm/mem_access.c b/xen/arch/x86/mm/mem_access.c
index e1522a0b75..4d49025cbe 100644
--- a/xen/arch/x86/mm/mem_access.c
+++ b/xen/arch/x86/mm/mem_access.c
@@ -495,6 +495,61 @@ void arch_p2m_set_access_required(struct domain *d, bool access_required)
     }
 }
 
+/*
+ * Set/clear the #VE suppress bit for a page.  Only available on VMX.
+ */
+int p2m_set_suppress_ve(struct domain *d, gfn_t gfn, bool suppress_ve,
+                        unsigned int altp2m_idx)
+{
+    struct p2m_domain *host_p2m = p2m_get_hostp2m(d);
+    struct p2m_domain *ap2m = NULL;
+    struct p2m_domain *p2m;
+    mfn_t mfn;
+    p2m_access_t a;
+    p2m_type_t t;
+    int rc;
+
+    if ( !cpu_has_vmx_virt_exceptions )
+        return -EOPNOTSUPP;
+
+    /* #VE should be enabled for this vcpu. */
+    if ( gfn_eq(vcpu_altp2m(current).veinfo_gfn, INVALID_GFN) )
+        return -ENXIO;
+
+    if ( altp2m_idx > 0 )
+    {
+        if ( altp2m_idx >= MAX_ALTP2M ||
+             d->arch.altp2m_eptp[altp2m_idx] == mfn_x(INVALID_MFN) )
+            return -EINVAL;
+
+        p2m = ap2m = d->arch.altp2m_p2m[altp2m_idx];
+    }
+    else
+        p2m = host_p2m;
+
+    gfn_lock(host_p2m, gfn, 0);
+
+    if ( ap2m )
+        p2m_lock(ap2m);
+
+    mfn = p2m->get_entry(p2m, gfn, &t, &a, 0, NULL, NULL);
+    if ( !mfn_valid(mfn) )
+    {
+        rc = -ESRCH;
+        goto out;
+    }
+
+    rc = p2m->set_entry(p2m, gfn, mfn, PAGE_ORDER_4K, t, a, suppress_ve);
+
+out:
+    if ( ap2m )
+        p2m_unlock(ap2m);
+
+    gfn_unlock(host_p2m, gfn, 0);
+
+    return rc;
+}
+
 /*
  * Local variables:
  * mode: C
diff --git a/xen/include/public/hvm/hvm_op.h b/xen/include/public/hvm/hvm_op.h
index bbba99e5f5..14d29d1700 100644
--- a/xen/include/public/hvm/hvm_op.h
+++ b/xen/include/public/hvm/hvm_op.h
@@ -38,6 +38,14 @@ struct xen_hvm_param {
 typedef struct xen_hvm_param xen_hvm_param_t;
 DEFINE_XEN_GUEST_HANDLE(xen_hvm_param_t);
 
+struct xen_hvm_altp2m_suppress_ve {
+    uint16_t view;
+    uint8_t suppress_ve; /* Boolean type. */
+    uint8_t pad1;
+    uint32_t pad2;
+    uint64_t gfn;
+};
+
 #if __XEN_INTERFACE_VERSION__ < 0x00040900
 
 /* Set the logical level of one of a domain's PCI INTx wires. */
@@ -296,6 +304,8 @@ struct xen_hvm_altp2m_op {
 #define HVMOP_altp2m_change_gfn           8
 /* Set access for an array of pages */
 #define HVMOP_altp2m_set_mem_access_multi 9
+/* Set the "Suppress #VE" bit on a page */
+#define HVMOP_altp2m_set_suppress_ve      10
     domid_t domain;
     uint16_t pad1;
     uint32_t pad2;
@@ -306,6 +316,7 @@ struct xen_hvm_altp2m_op {
         struct xen_hvm_altp2m_set_mem_access       set_mem_access;
         struct xen_hvm_altp2m_change_gfn           change_gfn;
         struct xen_hvm_altp2m_set_mem_access_multi set_mem_access_multi;
+        struct xen_hvm_altp2m_suppress_ve          suppress_ve;
         uint8_t pad[64];
     } u;
 };
diff --git a/xen/include/xen/mem_access.h b/xen/include/xen/mem_access.h
index 7e95eab81c..a8d38b90e6 100644
--- a/xen/include/xen/mem_access.h
+++ b/xen/include/xen/mem_access.h
@@ -72,6 +72,9 @@ long p2m_set_mem_access_multi(struct domain *d,
                               uint32_t nr, uint32_t start, uint32_t mask,
                               unsigned int altp2m_idx);
 
+int p2m_set_suppress_ve(struct domain *d, gfn_t gfn, bool suppress_ve,
+                        unsigned int altp2m_idx);
+
 /*
  * Get access type for a gfn.
  * If gfn == INVALID_GFN, gets the default access type.
-- 
2.18.0


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