[PATCH v8 0/5] x86/ioreq server: Introduce HVMMEM_ioreq_server mem type.

[PATCH v8 0/5] x86/ioreq server: Introduce HVMMEM_ioreq_server mem type.

[Yu Zhang]

XenGT leverages ioreq server to track and forward the accesses to GPU 
I/O resources, e.g. the PPGTT(per-process graphic translation tables).
Currently, ioreq server uses rangeset to track the BDF/ PIO/MMIO ranges
to be emulated. To select an ioreq server, the rangeset is searched to
see if the I/O range is recorded. However, number of ram pages to be
tracked may exceed the upper limit of rangeset.

Previously, one solution was proposed to refactor the rangeset, and 
extend its upper limit. However, after 12 rounds discussion, we have
decided to drop this approach due to security concerns. Now this new 
patch series introduces a new mem type, HVMMEM_ioreq_server, and added
hvm operations to let one ioreq server to claim its ownership of ram 
pages with this type. Accesses to a page of this type will be handled
by the specified ioreq server directly. 

Yu Zhang (5):
  x86/ioreq server: Release the p2m lock after mmio is handled.
  x86/ioreq server: Add DMOP to map guest ram with p2m_ioreq_server to
    an ioreq server.
  x86/ioreq server: Handle read-modify-write cases for p2m_ioreq_server
    pages.
  ix86/ioreq server: Asynchronously reset outstanding p2m_ioreq_server
    entries.
  x86/ioreq server: Synchronously reset outstanding p2m_ioreq_server
    entries when an ioreq server unmaps.

 xen/arch/x86/hvm/dm.c            |  72 ++++++++++++++++++++++-
 xen/arch/x86/hvm/emulate.c       |  99 +++++++++++++++++++++++++++++--
 xen/arch/x86/hvm/hvm.c           |   8 +--
 xen/arch/x86/hvm/ioreq.c         |  46 +++++++++++++++
 xen/arch/x86/mm/hap/hap.c        |   9 +++
 xen/arch/x86/mm/hap/nested_hap.c |   2 +-
 xen/arch/x86/mm/p2m-ept.c        |  16 ++++-
 xen/arch/x86/mm/p2m-pt.c         |  32 +++++++---
 xen/arch/x86/mm/p2m.c            | 123 +++++++++++++++++++++++++++++++++++++++
 xen/arch/x86/mm/shadow/multi.c   |   3 +-
 xen/include/asm-x86/hvm/ioreq.h  |   2 +
 xen/include/asm-x86/p2m.h        |  42 +++++++++++--
 xen/include/public/hvm/dm_op.h   |  28 +++++++++
 xen/include/public/hvm/hvm_op.h  |   8 ++-
 14 files changed, 460 insertions(+), 30 deletions(-)

-- 
1.9.1


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[PATCH v8 1/5] x86/ioreq server: Release the p2m lock after mmio is handled.

[Yu Zhang]

Routine hvmemul_do_io() may need to peek the p2m type of a gfn to
select the ioreq server. For example, operations on gfns with
p2m_ioreq_server type will be delivered to a corresponding ioreq
server, and this requires that the p2m type not be switched back
to p2m_ram_rw during the emulation process. To avoid this race
condition, we delay the release of p2m lock in hvm_hap_nested_page_fault()
until mmio is handled.

Note: previously in hvm_hap_nested_page_fault(), put_gfn() was moved
before the handling of mmio, due to a deadlock risk between the p2m
lock and the event lock(in commit 77b8dfe). Later, a per-event channel
lock was introduced in commit de6acb7, to send events. So we do not
need to worry about the deadlock issue.

Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
---
Cc: Paul Durrant <paul.durrant@citrix.com>
Cc: Jan Beulich <jbeulich@suse.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
---
 xen/arch/x86/hvm/hvm.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index ccfae4f..a9db7f7 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -1870,18 +1870,14 @@ int hvm_hap_nested_page_fault(paddr_t gpa, unsigned long gla,
          (npfec.write_access &&
           (p2m_is_discard_write(p2mt) || (p2mt == p2m_ioreq_server))) )
     {
-        __put_gfn(p2m, gfn);
-        if ( ap2m_active )
-            __put_gfn(hostp2m, gfn);
-
         rc = 0;
         if ( unlikely(is_pvh_domain(currd)) )
-            goto out;
+            goto out_put_gfn;
 
         if ( !handle_mmio_with_translation(gla, gpa >> PAGE_SHIFT, npfec) )
             hvm_inject_hw_exception(TRAP_gp_fault, 0);
         rc = 1;
-        goto out;
+        goto out_put_gfn;
     }
 
     /* Check if the page has been paged out */
-- 
1.9.1


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[PATCH v8 2/5] x86/ioreq server: Add DMOP to map guest ram with p2m_ioreq_server to an ioreq server.

[Yu Zhang]

A new DMOP - XEN_DMOP_map_mem_type_to_ioreq_server, is added to
let one ioreq server claim/disclaim its responsibility for the
handling of guest pages with p2m type p2m_ioreq_server. Users
of this DMOP can specify which kind of operation is supposed
to be emulated in a parameter named flags. Currently, this DMOP
only support the emulation of write operations. And it can be
further extended to support the emulation of read ones if an
ioreq server has such requirement in the future.

For now, we only support one ioreq server for this p2m type, so
once an ioreq server has claimed its ownership, subsequent calls
of the XEN_DMOP_map_mem_type_to_ioreq_server will fail. Users can
also disclaim the ownership of guest ram pages with p2m_ioreq_server,
by triggering this new DMOP, with ioreq server id set to the current
owner's and flags parameter set to 0.

Note both XEN_DMOP_map_mem_type_to_ioreq_server and p2m_ioreq_server
are only supported for HVMs with HAP enabled.

Also note that only after one ioreq server claims its ownership
of p2m_ioreq_server, will the p2m type change to p2m_ioreq_server
be allowed.

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com>
Acked-by: Tim Deegan <tim@xen.org>
---
Cc: Jan Beulich <jbeulich@suse.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Paul Durrant <paul.durrant@citrix.com>
Cc: George Dunlap <george.dunlap@eu.citrix.com>
Cc: Jun Nakajima <jun.nakajima@intel.com>
Cc: Kevin Tian <kevin.tian@intel.com>
Cc: Tim Deegan <tim@xen.org>

chagnes in v8:
  - According to comments from Jan & Paul: comments changes in hvmemul_do_io().
  - According to comments from Jan: remove the redundant code which would only
    be useful for read emulations.
  - According to comments from Jan: change interface which maps mem type to
    ioreq server, removed uint16_t pad and added an uint64_t opaque.
  - Address other comments from Jan, i.e. correct return values; remove stray
    cast.

changes in v7:
  - Use new ioreq server interface - XEN_DMOP_map_mem_type_to_ioreq_server.
  - According to comments from George: removed domain_pause/unpause() in
    hvm_map_mem_type_to_ioreq_server(), because it's too expensive,
    and we can avoid the:
    a> deadlock issue existed in v6 patch, between p2m lock and ioreq server
       lock by using these locks in the same order - solved in patch 4;
    b> for race condition between vm exit and ioreq server unbinding, we can
       just retry this instruction.
  - According to comments from Jan and George: continue to clarify logic in
    hvmemul_do_io().
  - According to comments from Jan: clarify comment in p2m_set_ioreq_server().

changes in v6:
  - Clarify logic in hvmemul_do_io().
  - Use recursive lock for ioreq server lock.
  - Remove debug print when mapping ioreq server.
  - Clarify code in ept_p2m_type_to_flags() for consistency.
  - Remove definition of P2M_IOREQ_HANDLE_WRITE_ACCESS.
  - Add comments for HVMMEM_ioreq_server to note only changes
    to/from HVMMEM_ram_rw are permitted.
  - Add domain_pause/unpause() in hvm_map_mem_type_to_ioreq_server()
    to avoid the race condition when a vm exit happens on a write-
    protected page, just to find the ioreq server has been unmapped
    already.
  - Introduce a seperate patch to delay the release of p2m
    lock to avoid the race condition.
  - Introduce a seperate patch to handle the read-modify-write
    operations on a write protected page.

changes in v5:
  - Simplify logic in hvmemul_do_io().
  - Use natual width types instead of fixed width types when possible.
  - Do not grant executable permission for p2m_ioreq_server entries.
  - Clarify comments and commit message.
  - Introduce a seperate patch to recalculate the p2m types after
    the ioreq server unmaps the p2m_ioreq_server.

changes in v4:
  - According to Paul's advice, add comments around the definition
    of HVMMEM_iore_server in hvm_op.h.
  - According to Wei Liu's comments, change the format of the commit
    message.

changes in v3:
  - Only support write emulation in this patch;
  - Remove the code to handle race condition in hvmemul_do_io(),
  - No need to reset the p2m type after an ioreq server has disclaimed
    its ownership of p2m_ioreq_server;
  - Only allow p2m type change to p2m_ioreq_server after an ioreq
    server has claimed its ownership of p2m_ioreq_server;
  - Only allow p2m type change to p2m_ioreq_server from pages with type
    p2m_ram_rw, and vice versa;
  - HVMOP_map_mem_type_to_ioreq_server interface change - use uint16,
    instead of enum to specify the memory type;
  - Function prototype change to p2m_get_ioreq_server();
  - Coding style changes;
  - Commit message changes;
  - Add Tim's Acked-by.

changes in v2:
  - Only support HAP enabled HVMs;
  - Replace p2m_mem_type_changed() with p2m_change_entry_type_global()
    to reset the p2m type, when an ioreq server tries to claim/disclaim
    its ownership of p2m_ioreq_server;
  - Comments changes.
---
 xen/arch/x86/hvm/dm.c            | 37 ++++++++++++++++++--
 xen/arch/x86/hvm/emulate.c       | 65 ++++++++++++++++++++++++++++++++---
 xen/arch/x86/hvm/ioreq.c         | 38 +++++++++++++++++++++
 xen/arch/x86/mm/hap/nested_hap.c |  2 +-
 xen/arch/x86/mm/p2m-ept.c        |  8 ++++-
 xen/arch/x86/mm/p2m-pt.c         | 19 +++++++----
 xen/arch/x86/mm/p2m.c            | 74 ++++++++++++++++++++++++++++++++++++++++
 xen/arch/x86/mm/shadow/multi.c   |  3 +-
 xen/include/asm-x86/hvm/ioreq.h  |  2 ++
 xen/include/asm-x86/p2m.h        | 26 ++++++++++++--
 xen/include/public/hvm/dm_op.h   | 28 +++++++++++++++
 xen/include/public/hvm/hvm_op.h  |  8 ++++-
 12 files changed, 290 insertions(+), 20 deletions(-)

diff --git a/xen/arch/x86/hvm/dm.c b/xen/arch/x86/hvm/dm.c
index 2122c45..1619feb 100644
--- a/xen/arch/x86/hvm/dm.c
+++ b/xen/arch/x86/hvm/dm.c
@@ -173,9 +173,14 @@ static int modified_memory(struct domain *d,
 
 static bool allow_p2m_type_change(p2m_type_t old, p2m_type_t new)
 {
+    if ( new == p2m_ioreq_server )
+        return old == p2m_ram_rw;
+
+    if ( old == p2m_ioreq_server )
+        return new == p2m_ram_rw;
+
     return p2m_is_ram(old) ||
-           (p2m_is_hole(old) && new == p2m_mmio_dm) ||
-           (old == p2m_ioreq_server && new == p2m_ram_rw);
+           (p2m_is_hole(old) && new == p2m_mmio_dm);
 }
 
 static int set_mem_type(struct domain *d,
@@ -202,6 +207,19 @@ static int set_mem_type(struct domain *d,
          unlikely(data->mem_type == HVMMEM_unused) )
         return -EINVAL;
 
+    if ( data->mem_type  == HVMMEM_ioreq_server )
+    {
+        unsigned int flags;
+
+        /* HVMMEM_ioreq_server is only supported for HAP enabled hvm. */
+        if ( !hap_enabled(d) )
+            return -EOPNOTSUPP;
+
+        /* Do not change to HVMMEM_ioreq_server if no ioreq server mapped. */
+        if ( !p2m_get_ioreq_server(d, &flags) )
+            return -EINVAL;
+    }
+
     while ( iter < data->nr )
     {
         unsigned long pfn = data->first_pfn + iter;
@@ -365,6 +383,21 @@ static int dm_op(domid_t domid,
         break;
     }
 
+    case XEN_DMOP_map_mem_type_to_ioreq_server:
+    {
+        const struct xen_dm_op_map_mem_type_to_ioreq_server *data =
+            &op.u.map_mem_type_to_ioreq_server;
+
+        rc = -EOPNOTSUPP;
+        /* Only support for HAP enabled hvm. */
+        if ( !hap_enabled(d) )
+            break;
+
+        rc = hvm_map_mem_type_to_ioreq_server(d, data->id,
+                                              data->type, data->flags);
+        break;
+    }
+
     case XEN_DMOP_set_ioreq_server_state:
     {
         const struct xen_dm_op_set_ioreq_server_state *data =
diff --git a/xen/arch/x86/hvm/emulate.c b/xen/arch/x86/hvm/emulate.c
index f36d7c9..37139e6 100644
--- a/xen/arch/x86/hvm/emulate.c
+++ b/xen/arch/x86/hvm/emulate.c
@@ -99,6 +99,7 @@ static int hvmemul_do_io(
     uint8_t dir, bool_t df, bool_t data_is_addr, uintptr_t data)
 {
     struct vcpu *curr = current;
+    struct domain *currd = curr->domain;
     struct hvm_vcpu_io *vio = &curr->arch.hvm_vcpu.hvm_io;
     ioreq_t p = {
         .type = is_mmio ? IOREQ_TYPE_COPY : IOREQ_TYPE_PIO,
@@ -140,7 +141,7 @@ static int hvmemul_do_io(
              (p.dir != dir) ||
              (p.df != df) ||
              (p.data_is_ptr != data_is_addr) )
-            domain_crash(curr->domain);
+            domain_crash(currd);
 
         if ( data_is_addr )
             return X86EMUL_UNHANDLEABLE;
@@ -177,8 +178,64 @@ static int hvmemul_do_io(
         break;
     case X86EMUL_UNHANDLEABLE:
     {
-        struct hvm_ioreq_server *s =
-            hvm_select_ioreq_server(curr->domain, &p);
+        /*
+         * Xen isn't emulating the instruction internally, so see if
+         * there's an ioreq server that can handle it. Rules:
+         *
+         * - PIO and "normal" MMIO run through hvm_select_ioreq_server()
+         * to choose the ioreq server by range. If no server is found,
+         * the access is ignored.
+         *
+         * - p2m_ioreq_server accesses are handled by the designated
+         * ioreq_server for the domain, but there are some corner
+         * cases:
+         *
+         *   - If the domain ioreq_server is NULL, assume there is a
+         *   race between the unbinding of ioreq server and guest fault
+         *   so re-try the instruction.
+         */
+        struct hvm_ioreq_server *s = NULL;
+        p2m_type_t p2mt = p2m_invalid;
+
+        if ( is_mmio )
+        {
+            unsigned long gmfn = paddr_to_pfn(addr);
+
+            get_gfn_query_unlocked(currd, gmfn, &p2mt);
+
+            if ( p2mt == p2m_ioreq_server )
+            {
+                unsigned int flags;
+
+                /*
+                 * Value of s could be stale, when we lost a race
+                 * with dm_op which unmaps p2m_ioreq_server from the
+                 * ioreq server. Yet there's no cheap way to avoid
+                 * this, so device model need to do the check.
+                 */
+                s = p2m_get_ioreq_server(currd, &flags);
+
+                /*
+                 * If p2mt is ioreq_server but ioreq_server is NULL,
+                 * we probably lost a race with unbinding of ioreq
+                 * server, just retry the access.
+                 */
+                if ( s == NULL )
+                {
+                    rc = X86EMUL_RETRY;
+                    vio->io_req.state = STATE_IOREQ_NONE;
+                    break;
+                }
+            }
+        }
+
+        /*
+         * Value of s could be stale, when we lost a race with dm_op
+         * which unmaps this PIO/MMIO address from the ioreq server.
+         * The device model side need to do the check.
+         */
+        if ( !s )
+            s = hvm_select_ioreq_server(currd, &p);
 
         /* If there is no suitable backing DM, just ignore accesses */
         if ( !s )
@@ -189,7 +246,7 @@ static int hvmemul_do_io(
         else
         {
             rc = hvm_send_ioreq(s, &p, 0);
-            if ( rc != X86EMUL_RETRY || curr->domain->is_shutting_down )
+            if ( rc != X86EMUL_RETRY || currd->is_shutting_down )
                 vio->io_req.state = STATE_IOREQ_NONE;
             else if ( data_is_addr )
                 rc = X86EMUL_OKAY;
diff --git a/xen/arch/x86/hvm/ioreq.c b/xen/arch/x86/hvm/ioreq.c
index ebb3eca..fcb9f38 100644
--- a/xen/arch/x86/hvm/ioreq.c
+++ b/xen/arch/x86/hvm/ioreq.c
@@ -753,6 +753,8 @@ int hvm_destroy_ioreq_server(struct domain *d, ioservid_t id)
 
         domain_pause(d);
 
+        p2m_destroy_ioreq_server(d, s);
+
         hvm_ioreq_server_disable(s, 0);
 
         list_del(&s->list_entry);
@@ -914,6 +916,42 @@ int hvm_unmap_io_range_from_ioreq_server(struct domain *d, ioservid_t id,
     return rc;
 }
 
+int hvm_map_mem_type_to_ioreq_server(struct domain *d, ioservid_t id,
+                                     uint32_t type, uint32_t flags)
+{
+    struct hvm_ioreq_server *s;
+    int rc;
+
+    /* For now, only HVMMEM_ioreq_server is supported. */
+    if ( type != HVMMEM_ioreq_server )
+        return -EINVAL;
+
+    /* For now, only write emulation is supported. */
+    if ( flags & ~(XEN_DMOP_IOREQ_MEM_ACCESS_WRITE) )
+        return -EINVAL;
+
+    spin_lock_recursive(&d->arch.hvm_domain.ioreq_server.lock);
+
+    rc = -ENOENT;
+    list_for_each_entry ( s,
+                          &d->arch.hvm_domain.ioreq_server.list,
+                          list_entry )
+    {
+        if ( s == d->arch.hvm_domain.default_ioreq_server )
+            continue;
+
+        if ( s->id == id )
+        {
+            rc = p2m_set_ioreq_server(d, flags, s);
+            break;
+        }
+    }
+
+    spin_unlock_recursive(&d->arch.hvm_domain.ioreq_server.lock);
+
+    return rc;
+}
+
 int hvm_set_ioreq_server_state(struct domain *d, ioservid_t id,
                                bool_t enabled)
 {
diff --git a/xen/arch/x86/mm/hap/nested_hap.c b/xen/arch/x86/mm/hap/nested_hap.c
index 162afed..408ea7f 100644
--- a/xen/arch/x86/mm/hap/nested_hap.c
+++ b/xen/arch/x86/mm/hap/nested_hap.c
@@ -172,7 +172,7 @@ nestedhap_walk_L0_p2m(struct p2m_domain *p2m, paddr_t L1_gpa, paddr_t *L0_gpa,
     if ( *p2mt == p2m_mmio_direct )
         goto direct_mmio_out;
     rc = NESTEDHVM_PAGEFAULT_MMIO;
-    if ( *p2mt == p2m_mmio_dm )
+    if ( *p2mt == p2m_mmio_dm || *p2mt == p2m_ioreq_server )
         goto out;
 
     rc = NESTEDHVM_PAGEFAULT_L0_ERROR;
diff --git a/xen/arch/x86/mm/p2m-ept.c b/xen/arch/x86/mm/p2m-ept.c
index 568944f..cc1eb21 100644
--- a/xen/arch/x86/mm/p2m-ept.c
+++ b/xen/arch/x86/mm/p2m-ept.c
@@ -131,6 +131,13 @@ static void ept_p2m_type_to_flags(struct p2m_domain *p2m, ept_entry_t *entry,
             entry->r = entry->w = entry->x = 1;
             entry->a = entry->d = !!cpu_has_vmx_ept_ad;
             break;
+        case p2m_ioreq_server:
+            entry->r = 1;
+            entry->w = !(p2m->ioreq.flags & XEN_DMOP_IOREQ_MEM_ACCESS_WRITE);
+            entry->x = 0;
+            entry->a = !!cpu_has_vmx_ept_ad;
+            entry->d = entry->w && entry->a;
+            break;
         case p2m_mmio_direct:
             entry->r = entry->x = 1;
             entry->w = !rangeset_contains_singleton(mmio_ro_ranges,
@@ -170,7 +177,6 @@ static void ept_p2m_type_to_flags(struct p2m_domain *p2m, ept_entry_t *entry,
             entry->a = entry->d = !!cpu_has_vmx_ept_ad;
             break;
         case p2m_grant_map_ro:
-        case p2m_ioreq_server:
             entry->r = 1;
             entry->w = entry->x = 0;
             entry->a = !!cpu_has_vmx_ept_ad;
diff --git a/xen/arch/x86/mm/p2m-pt.c b/xen/arch/x86/mm/p2m-pt.c
index bbfa54e..7e11b99 100644
--- a/xen/arch/x86/mm/p2m-pt.c
+++ b/xen/arch/x86/mm/p2m-pt.c
@@ -70,7 +70,9 @@ static const unsigned long pgt[] = {
     PGT_l3_page_table
 };
 
-static unsigned long p2m_type_to_flags(p2m_type_t t, mfn_t mfn,
+static unsigned long p2m_type_to_flags(const struct p2m_domain *p2m,
+                                       p2m_type_t t,
+                                       mfn_t mfn,
                                        unsigned int level)
 {
     unsigned long flags;
@@ -92,8 +94,12 @@ static unsigned long p2m_type_to_flags(p2m_type_t t, mfn_t mfn,
     default:
         return flags | _PAGE_NX_BIT;
     case p2m_grant_map_ro:
-    case p2m_ioreq_server:
         return flags | P2M_BASE_FLAGS | _PAGE_NX_BIT;
+    case p2m_ioreq_server:
+        flags |= P2M_BASE_FLAGS | _PAGE_RW | _PAGE_NX_BIT;
+        if ( p2m->ioreq.flags & XEN_DMOP_IOREQ_MEM_ACCESS_WRITE )
+            return flags & ~_PAGE_RW;
+        return flags;
     case p2m_ram_ro:
     case p2m_ram_logdirty:
     case p2m_ram_shared:
@@ -440,7 +446,8 @@ static int do_recalc(struct p2m_domain *p2m, unsigned long gfn)
             p2m_type_t p2mt = p2m_is_logdirty_range(p2m, gfn & mask, gfn | ~mask)
                               ? p2m_ram_logdirty : p2m_ram_rw;
             unsigned long mfn = l1e_get_pfn(e);
-            unsigned long flags = p2m_type_to_flags(p2mt, _mfn(mfn), level);
+            unsigned long flags = p2m_type_to_flags(p2m, p2mt,
+                                                    _mfn(mfn), level);
 
             if ( level )
             {
@@ -578,7 +585,7 @@ p2m_pt_set_entry(struct p2m_domain *p2m, unsigned long gfn, mfn_t mfn,
         ASSERT(!mfn_valid(mfn) || p2mt != p2m_mmio_direct);
         l3e_content = mfn_valid(mfn) || p2m_allows_invalid_mfn(p2mt)
             ? l3e_from_pfn(mfn_x(mfn),
-                           p2m_type_to_flags(p2mt, mfn, 2) | _PAGE_PSE)
+                           p2m_type_to_flags(p2m, p2mt, mfn, 2) | _PAGE_PSE)
             : l3e_empty();
         entry_content.l1 = l3e_content.l3;
 
@@ -615,7 +622,7 @@ p2m_pt_set_entry(struct p2m_domain *p2m, unsigned long gfn, mfn_t mfn,
 
         if ( mfn_valid(mfn) || p2m_allows_invalid_mfn(p2mt) )
             entry_content = p2m_l1e_from_pfn(mfn_x(mfn),
-                                             p2m_type_to_flags(p2mt, mfn, 0));
+                                         p2m_type_to_flags(p2m, p2mt, mfn, 0));
         else
             entry_content = l1e_empty();
 
@@ -652,7 +659,7 @@ p2m_pt_set_entry(struct p2m_domain *p2m, unsigned long gfn, mfn_t mfn,
         ASSERT(!mfn_valid(mfn) || p2mt != p2m_mmio_direct);
         if ( mfn_valid(mfn) || p2m_allows_invalid_mfn(p2mt) )
             l2e_content = l2e_from_pfn(mfn_x(mfn),
-                                       p2m_type_to_flags(p2mt, mfn, 1) |
+                                       p2m_type_to_flags(p2m, p2mt, mfn, 1) |
                                        _PAGE_PSE);
         else
             l2e_content = l2e_empty();
diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c
index 2eee9cd..0edfc61 100644
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -82,6 +82,8 @@ static int p2m_initialise(struct domain *d, struct p2m_domain *p2m)
     else
         p2m_pt_init(p2m);
 
+    spin_lock_init(&p2m->ioreq.lock);
+
     return ret;
 }
 
@@ -286,6 +288,78 @@ void p2m_memory_type_changed(struct domain *d)
     }
 }
 
+int p2m_set_ioreq_server(struct domain *d,
+                         unsigned int flags,
+                         struct hvm_ioreq_server *s)
+{
+    struct p2m_domain *p2m = p2m_get_hostp2m(d);
+    int rc;
+
+    /*
+     * Use lock to prevent concurrent setting attempts
+     * from multiple ioreq serers.
+     */
+    spin_lock(&p2m->ioreq.lock);
+
+    /* Unmap ioreq server from p2m type by passing flags with 0. */
+    if ( flags == 0 )
+    {
+        rc = -EINVAL;
+        if ( p2m->ioreq.server != s )
+            goto out;
+
+        p2m->ioreq.server = NULL;
+        p2m->ioreq.flags = 0;
+    }
+    else
+    {
+        rc = -EBUSY;
+        if ( p2m->ioreq.server != NULL )
+            goto out;
+
+        p2m->ioreq.server = s;
+        p2m->ioreq.flags = flags;
+    }
+
+    rc = 0;
+
+ out:
+    spin_unlock(&p2m->ioreq.lock);
+
+    return rc;
+}
+
+struct hvm_ioreq_server *p2m_get_ioreq_server(struct domain *d,
+                                              unsigned int *flags)
+{
+    struct p2m_domain *p2m = p2m_get_hostp2m(d);
+    struct hvm_ioreq_server *s;
+
+    spin_lock(&p2m->ioreq.lock);
+
+    s = p2m->ioreq.server;
+    *flags = p2m->ioreq.flags;
+
+    spin_unlock(&p2m->ioreq.lock);
+    return s;
+}
+
+void p2m_destroy_ioreq_server(const struct domain *d,
+                              const struct hvm_ioreq_server *s)
+{
+    struct p2m_domain *p2m = p2m_get_hostp2m(d);
+
+    spin_lock(&p2m->ioreq.lock);
+
+    if ( p2m->ioreq.server == s )
+    {
+        p2m->ioreq.server = NULL;
+        p2m->ioreq.flags = 0;
+    }
+
+    spin_unlock(&p2m->ioreq.lock);
+}
+
 void p2m_enable_hardware_log_dirty(struct domain *d)
 {
     struct p2m_domain *p2m = p2m_get_hostp2m(d);
diff --git a/xen/arch/x86/mm/shadow/multi.c b/xen/arch/x86/mm/shadow/multi.c
index 7ea9d81..521b639 100644
--- a/xen/arch/x86/mm/shadow/multi.c
+++ b/xen/arch/x86/mm/shadow/multi.c
@@ -3269,8 +3269,7 @@ static int sh_page_fault(struct vcpu *v,
     }
 
     /* Need to hand off device-model MMIO to the device model */
-    if ( p2mt == p2m_mmio_dm
-         || (p2mt == p2m_ioreq_server && ft == ft_demand_write) )
+    if ( p2mt == p2m_mmio_dm )
     {
         gpa = guest_walk_to_gpa(&gw);
         goto mmio;
diff --git a/xen/include/asm-x86/hvm/ioreq.h b/xen/include/asm-x86/hvm/ioreq.h
index fbf2c74..b43667a 100644
--- a/xen/include/asm-x86/hvm/ioreq.h
+++ b/xen/include/asm-x86/hvm/ioreq.h
@@ -37,6 +37,8 @@ int hvm_map_io_range_to_ioreq_server(struct domain *d, ioservid_t id,
 int hvm_unmap_io_range_from_ioreq_server(struct domain *d, ioservid_t id,
                                          uint32_t type, uint64_t start,
                                          uint64_t end);
+int hvm_map_mem_type_to_ioreq_server(struct domain *d, ioservid_t id,
+                                     uint32_t type, uint32_t flags);
 int hvm_set_ioreq_server_state(struct domain *d, ioservid_t id,
                                bool_t enabled);
 
diff --git a/xen/include/asm-x86/p2m.h b/xen/include/asm-x86/p2m.h
index 470d29d..3786680 100644
--- a/xen/include/asm-x86/p2m.h
+++ b/xen/include/asm-x86/p2m.h
@@ -89,7 +89,8 @@ typedef unsigned int p2m_query_t;
                        | p2m_to_mask(p2m_ram_paging_out)      \
                        | p2m_to_mask(p2m_ram_paged)           \
                        | p2m_to_mask(p2m_ram_paging_in)       \
-                       | p2m_to_mask(p2m_ram_shared))
+                       | p2m_to_mask(p2m_ram_shared)          \
+                       | p2m_to_mask(p2m_ioreq_server))
 
 /* Types that represent a physmap hole that is ok to replace with a shared
  * entry */
@@ -111,8 +112,7 @@ typedef unsigned int p2m_query_t;
 #define P2M_RO_TYPES (p2m_to_mask(p2m_ram_logdirty)     \
                       | p2m_to_mask(p2m_ram_ro)         \
                       | p2m_to_mask(p2m_grant_map_ro)   \
-                      | p2m_to_mask(p2m_ram_shared)     \
-                      | p2m_to_mask(p2m_ioreq_server))
+                      | p2m_to_mask(p2m_ram_shared))
 
 /* Write-discard types, which should discard the write operations */
 #define P2M_DISCARD_WRITE_TYPES (p2m_to_mask(p2m_ram_ro)     \
@@ -336,6 +336,20 @@ struct p2m_domain {
         struct ept_data ept;
         /* NPT-equivalent structure could be added here. */
     };
+
+     struct {
+         spinlock_t lock;
+         /*
+          * ioreq server who's responsible for the emulation of
+          * gfns with specific p2m type(for now, p2m_ioreq_server).
+          */
+         struct hvm_ioreq_server *server;
+         /*
+          * flags specifies whether read, write or both operations
+          * are to be emulated by an ioreq server.
+          */
+         unsigned int flags;
+     } ioreq;
 };
 
 /* get host p2m table */
@@ -827,6 +841,12 @@ static inline unsigned int p2m_get_iommu_flags(p2m_type_t p2mt, mfn_t mfn)
     return flags;
 }
 
+int p2m_set_ioreq_server(struct domain *d, unsigned int flags,
+                         struct hvm_ioreq_server *s);
+struct hvm_ioreq_server *p2m_get_ioreq_server(struct domain *d,
+                                              unsigned int *flags);
+void p2m_destroy_ioreq_server(const struct domain *d, const struct hvm_ioreq_server *s);
+
 #endif /* _XEN_ASM_X86_P2M_H */
 
 /*
diff --git a/xen/include/public/hvm/dm_op.h b/xen/include/public/hvm/dm_op.h
index f54cece..2a36833 100644
--- a/xen/include/public/hvm/dm_op.h
+++ b/xen/include/public/hvm/dm_op.h
@@ -318,6 +318,32 @@ struct xen_dm_op_inject_msi {
     uint64_aligned_t addr;
 };
 
+/*
+ * XEN_DMOP_map_mem_type_to_ioreq_server : map or unmap the IOREQ Server <id>
+ *                                      to specific memroy type <type>
+ *                                      for specific accesses <flags>
+ *
+ * For now, flags only accept the value of XEN_DMOP_IOREQ_MEM_ACCESS_WRITE,
+ * which means only write operations are to be forwarded to an ioreq server.
+ * Support for the emulation of read operations can be added when an ioreq
+ * server has such requirement in future.
+ */
+#define XEN_DMOP_map_mem_type_to_ioreq_server 15
+
+struct xen_dm_op_map_mem_type_to_ioreq_server {
+    ioservid_t id;      /* IN - ioreq server id */
+    uint16_t type;      /* IN - memory type */
+    uint32_t flags;     /* IN - types of accesses to be forwarded to the
+                           ioreq server. flags with 0 means to unmap the
+                           ioreq server */
+
+#define XEN_DMOP_IOREQ_MEM_ACCESS_READ (1u << 0)
+#define XEN_DMOP_IOREQ_MEM_ACCESS_WRITE (1u << 1)
+
+    uint64_t opaque;    /* IN/OUT - only used for hypercall continuation,
+                           has to be set to zero by the caller */
+};
+
 struct xen_dm_op {
     uint32_t op;
     uint32_t pad;
@@ -336,6 +362,8 @@ struct xen_dm_op {
         struct xen_dm_op_set_mem_type set_mem_type;
         struct xen_dm_op_inject_event inject_event;
         struct xen_dm_op_inject_msi inject_msi;
+        struct xen_dm_op_map_mem_type_to_ioreq_server
+                map_mem_type_to_ioreq_server;
     } u;
 };
 
diff --git a/xen/include/public/hvm/hvm_op.h b/xen/include/public/hvm/hvm_op.h
index bc00ef0..0bdafdf 100644
--- a/xen/include/public/hvm/hvm_op.h
+++ b/xen/include/public/hvm/hvm_op.h
@@ -93,7 +93,13 @@ typedef enum {
     HVMMEM_unused,             /* Placeholder; setting memory to this type
                                   will fail for code after 4.7.0 */
 #endif
-    HVMMEM_ioreq_server
+    HVMMEM_ioreq_server        /* Memory type claimed by an ioreq server; type
+                                  changes to this value are only allowed after
+                                  an ioreq server has claimed its ownership.
+                                  Only pages with HVMMEM_ram_rw are allowed to
+                                  change to this type; conversely, pages with
+                                  this type are only allowed to be changed back
+                                  to HVMMEM_ram_rw. */
 } hvmmem_type_t;
 
 /* Hint from PV drivers for pagetable destruction. */
-- 
1.9.1


_______________________________________________
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Xen-devel@lists.xen.org
https://lists.xen.org/xen-devel

[PATCH v8 3/5] x86/ioreq server: Handle read-modify-write cases for p2m_ioreq_server pages.

[Yu Zhang]

In ept_handle_violation(), write violations are also treated as
read violations. And when a VM is accessing a write-protected
address with read-modify-write instructions, the read emulation
process is triggered first.

For p2m_ioreq_server pages, current ioreq server only forwards
the write operations to the device model. Therefore when such page
is being accessed by a read-modify-write instruction, the read
operations should be emulated here in hypervisor. This patch provides
such a handler to copy the data to the buffer.

Note: MMIOs with p2m_mmio_dm type do not need such special treatment
because both reads and writes will go to the device mode.

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com>
---
Cc: Paul Durrant <paul.durrant@citrix.com>
Cc: Jan Beulich <jbeulich@suse.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>

changes in v2: 
  - According to comments from Jan: clarify comments in hvmemul_do_io().

changes in v2: 
  - According to comments from Jan: rename mem_ops to ioreq_server_ops.
  - According to comments from Jan: use hvm_copy_from_guest_phys() in
    ioreq_server_read(), instead of do it by myself.
---
 xen/arch/x86/hvm/emulate.c | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)

diff --git a/xen/arch/x86/hvm/emulate.c b/xen/arch/x86/hvm/emulate.c
index 37139e6..52c726e 100644
--- a/xen/arch/x86/hvm/emulate.c
+++ b/xen/arch/x86/hvm/emulate.c
@@ -94,6 +94,26 @@ static const struct hvm_io_handler null_handler = {
     .ops = &null_ops
 };
 
+static int ioreq_server_read(const struct hvm_io_handler *io_handler,
+                    uint64_t addr,
+                    uint32_t size,
+                    uint64_t *data)
+{
+    if ( hvm_copy_from_guest_phys(data, addr, size) != HVMCOPY_okay )
+        return X86EMUL_UNHANDLEABLE;
+
+    return X86EMUL_OKAY;
+}
+
+static const struct hvm_io_ops ioreq_server_ops = {
+    .read = ioreq_server_read,
+    .write = null_write
+};
+
+static const struct hvm_io_handler ioreq_server_handler = {
+    .ops = &ioreq_server_ops
+};
+
 static int hvmemul_do_io(
     bool_t is_mmio, paddr_t addr, unsigned long *reps, unsigned int size,
     uint8_t dir, bool_t df, bool_t data_is_addr, uintptr_t data)
@@ -193,6 +213,9 @@ static int hvmemul_do_io(
          *   - If the domain ioreq_server is NULL, assume there is a
          *   race between the unbinding of ioreq server and guest fault
          *   so re-try the instruction.
+         *
+         *   - If the accesss is a read, this could be part of a
+         *   read-modify-write instruction, emulate the read first.
          */
         struct hvm_ioreq_server *s = NULL;
         p2m_type_t p2mt = p2m_invalid;
@@ -226,6 +249,17 @@ static int hvmemul_do_io(
                     vio->io_req.state = STATE_IOREQ_NONE;
                     break;
                 }
+
+                /*
+                 * This is part of a read-modify-write instruction.
+                 * Emulate the read part so we have the value cached.
+                 */
+                if ( dir == IOREQ_READ )
+                {
+                    rc = hvm_process_io_intercept(&ioreq_server_handler, &p);
+                    vio->io_req.state = STATE_IOREQ_NONE;
+                    break;
+                }
             }
         }
 
-- 
1.9.1


_______________________________________________
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Xen-devel@lists.xen.org
https://lists.xen.org/xen-devel

[PATCH v8 4/5] x86/ioreq server: Asynchronously reset outstanding p2m_ioreq_server entries.

[Yu Zhang]

After an ioreq server has unmapped, the remaining p2m_ioreq_server
entries need to be reset back to p2m_ram_rw. This patch does this
asynchronously with the current p2m_change_entry_type_global()
interface.

This patch also disallows live migration, when there's still any
outstanding p2m_ioreq_server entry left. The core reason is our
current implementation of p2m_change_entry_type_global() can not
tell the state of p2m_ioreq_server entries(can not decide if an
entry is to be emulated or to be resynced).

Note: new field entry_count is introduced in struct p2m_domain,
to record the number of p2m_ioreq_server p2m page table entries.
One nature of these entries is that they only point to 4K sized
page frames, because all p2m_ioreq_server entries are originated
from p2m_ram_rw ones in p2m_change_type_one(). We do not need to
worry about the counting for 2M/1G sized pages.

Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com>
---
Cc: Paul Durrant <paul.durrant@citrix.com>
Cc: Jan Beulich <jbeulich@suse.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: George Dunlap <george.dunlap@eu.citrix.com>
Cc: Jun Nakajima <jun.nakajima@intel.com>
Cc: Kevin Tian <kevin.tian@intel.com>

changes in v4: 
  - According to comments from Jan: use ASSERT() instead of 'if'
    condition in p2m_change_type_one().
  - According to comments from Jan: commit message changes to mention
    the p2m_ioreq_server are all based on 4K sized pages.

changes in v3: 
  - Move the synchronously resetting logic into patch 5.
  - According to comments from Jan: introduce p2m_check_changeable()
    to clarify the p2m type change code.
  - According to comments from George: use locks in the same order
    to avoid deadlock, call p2m_change_entry_type_global() after unmap
    of the ioreq server is finished.

changes in v2: 
  - Move the calculation of ioreq server page entry_cout into 
    p2m_change_type_one() so that we do not need a seperate lock.
    Note: entry_count is also calculated in resolve_misconfig()/
    do_recalc(), fortunately callers of both routines have p2m 
    lock protected already.
  - Simplify logic in hvmop_set_mem_type().
  - Introduce routine p2m_finish_type_change() to walk the p2m 
    table and do the p2m reset.
---
 xen/arch/x86/hvm/ioreq.c  |  8 ++++++++
 xen/arch/x86/mm/hap/hap.c |  9 +++++++++
 xen/arch/x86/mm/p2m-ept.c |  8 +++++++-
 xen/arch/x86/mm/p2m-pt.c  | 13 +++++++++++--
 xen/arch/x86/mm/p2m.c     | 20 ++++++++++++++++++++
 xen/include/asm-x86/p2m.h |  9 ++++++++-
 6 files changed, 63 insertions(+), 4 deletions(-)

diff --git a/xen/arch/x86/hvm/ioreq.c b/xen/arch/x86/hvm/ioreq.c
index fcb9f38..c129eb4 100644
--- a/xen/arch/x86/hvm/ioreq.c
+++ b/xen/arch/x86/hvm/ioreq.c
@@ -949,6 +949,14 @@ int hvm_map_mem_type_to_ioreq_server(struct domain *d, ioservid_t id,
 
     spin_unlock_recursive(&d->arch.hvm_domain.ioreq_server.lock);
 
+    if ( rc == 0 && flags == 0 )
+    {
+        struct p2m_domain *p2m = p2m_get_hostp2m(d);
+
+        if ( read_atomic(&p2m->ioreq.entry_count) )
+            p2m_change_entry_type_global(d, p2m_ioreq_server, p2m_ram_rw);
+    }
+
     return rc;
 }
 
diff --git a/xen/arch/x86/mm/hap/hap.c b/xen/arch/x86/mm/hap/hap.c
index a57b385..6ec950a 100644
--- a/xen/arch/x86/mm/hap/hap.c
+++ b/xen/arch/x86/mm/hap/hap.c
@@ -187,6 +187,15 @@ out:
  */
 static int hap_enable_log_dirty(struct domain *d, bool_t log_global)
 {
+    struct p2m_domain *p2m = p2m_get_hostp2m(d);
+
+    /*
+     * Refuse to turn on global log-dirty mode if
+     * there's outstanding p2m_ioreq_server pages.
+     */
+    if ( log_global && read_atomic(&p2m->ioreq.entry_count) )
+        return -EBUSY;
+
     /* turn on PG_log_dirty bit in paging mode */
     paging_lock(d);
     d->arch.paging.mode |= PG_log_dirty;
diff --git a/xen/arch/x86/mm/p2m-ept.c b/xen/arch/x86/mm/p2m-ept.c
index cc1eb21..1df3d09 100644
--- a/xen/arch/x86/mm/p2m-ept.c
+++ b/xen/arch/x86/mm/p2m-ept.c
@@ -544,6 +544,12 @@ static int resolve_misconfig(struct p2m_domain *p2m, unsigned long gfn)
                     e.ipat = ipat;
                     if ( e.recalc && p2m_is_changeable(e.sa_p2mt) )
                     {
+                         if ( e.sa_p2mt == p2m_ioreq_server )
+                         {
+                             p2m->ioreq.entry_count--;
+                             ASSERT(p2m->ioreq.entry_count >= 0);
+                         }
+
                          e.sa_p2mt = p2m_is_logdirty_range(p2m, gfn + i, gfn + i)
                                      ? p2m_ram_logdirty : p2m_ram_rw;
                          ept_p2m_type_to_flags(p2m, &e, e.sa_p2mt, e.access);
@@ -965,7 +971,7 @@ static mfn_t ept_get_entry(struct p2m_domain *p2m,
     if ( is_epte_valid(ept_entry) )
     {
         if ( (recalc || ept_entry->recalc) &&
-             p2m_is_changeable(ept_entry->sa_p2mt) )
+             p2m_check_changeable(ept_entry->sa_p2mt) )
             *t = p2m_is_logdirty_range(p2m, gfn, gfn) ? p2m_ram_logdirty
                                                       : p2m_ram_rw;
         else
diff --git a/xen/arch/x86/mm/p2m-pt.c b/xen/arch/x86/mm/p2m-pt.c
index 7e11b99..13c7014 100644
--- a/xen/arch/x86/mm/p2m-pt.c
+++ b/xen/arch/x86/mm/p2m-pt.c
@@ -436,11 +436,13 @@ static int do_recalc(struct p2m_domain *p2m, unsigned long gfn)
          needs_recalc(l1, *pent) )
     {
         l1_pgentry_t e = *pent;
+        p2m_type_t p2mt_old;
 
         if ( !valid_recalc(l1, e) )
             P2M_DEBUG("bogus recalc leaf at d%d:%lx:%u\n",
                       p2m->domain->domain_id, gfn, level);
-        if ( p2m_is_changeable(p2m_flags_to_type(l1e_get_flags(e))) )
+        p2mt_old = p2m_flags_to_type(l1e_get_flags(e));
+        if ( p2m_is_changeable(p2mt_old) )
         {
             unsigned long mask = ~0UL << (level * PAGETABLE_ORDER);
             p2m_type_t p2mt = p2m_is_logdirty_range(p2m, gfn & mask, gfn | ~mask)
@@ -460,6 +462,13 @@ static int do_recalc(struct p2m_domain *p2m, unsigned long gfn)
                      mfn &= ~(_PAGE_PSE_PAT >> PAGE_SHIFT);
                 flags |= _PAGE_PSE;
             }
+
+            if ( p2mt_old == p2m_ioreq_server )
+            {
+                p2m->ioreq.entry_count--;
+                ASSERT(p2m->ioreq.entry_count >= 0);
+            }
+
             e = l1e_from_pfn(mfn, flags);
             p2m_add_iommu_flags(&e, level,
                                 (p2mt == p2m_ram_rw)
@@ -729,7 +738,7 @@ p2m_pt_set_entry(struct p2m_domain *p2m, unsigned long gfn, mfn_t mfn,
 static inline p2m_type_t recalc_type(bool_t recalc, p2m_type_t t,
                                      struct p2m_domain *p2m, unsigned long gfn)
 {
-    if ( !recalc || !p2m_is_changeable(t) )
+    if ( !recalc || !p2m_check_changeable(t) )
         return t;
     return p2m_is_logdirty_range(p2m, gfn, gfn) ? p2m_ram_logdirty
                                                 : p2m_ram_rw;
diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c
index 0edfc61..87f274d 100644
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -954,6 +954,26 @@ int p2m_change_type_one(struct domain *d, unsigned long gfn,
                          p2m->default_access)
          : -EBUSY;
 
+    if ( !rc )
+    {
+        switch ( nt )
+        {
+        case p2m_ram_rw:
+            if ( ot == p2m_ioreq_server )
+            {
+                p2m->ioreq.entry_count--;
+                ASSERT(p2m->ioreq.entry_count >= 0);
+            }
+            break;
+        case p2m_ioreq_server:
+            ASSERT(ot == p2m_ram_rw);
+            p2m->ioreq.entry_count++;
+            break;
+        default:
+            break;
+        }
+    }
+
     gfn_unlock(p2m, gfn, 0);
 
     return rc;
diff --git a/xen/include/asm-x86/p2m.h b/xen/include/asm-x86/p2m.h
index 3786680..395f125 100644
--- a/xen/include/asm-x86/p2m.h
+++ b/xen/include/asm-x86/p2m.h
@@ -120,7 +120,10 @@ typedef unsigned int p2m_query_t;
 
 /* Types that can be subject to bulk transitions. */
 #define P2M_CHANGEABLE_TYPES (p2m_to_mask(p2m_ram_rw) \
-                              | p2m_to_mask(p2m_ram_logdirty) )
+                              | p2m_to_mask(p2m_ram_logdirty) \
+                              | p2m_to_mask(p2m_ioreq_server) )
+
+#define P2M_IOREQ_TYPES (p2m_to_mask(p2m_ioreq_server))
 
 #define P2M_POD_TYPES (p2m_to_mask(p2m_populate_on_demand))
 
@@ -157,6 +160,7 @@ typedef unsigned int p2m_query_t;
 #define p2m_is_readonly(_t) (p2m_to_mask(_t) & P2M_RO_TYPES)
 #define p2m_is_discard_write(_t) (p2m_to_mask(_t) & P2M_DISCARD_WRITE_TYPES)
 #define p2m_is_changeable(_t) (p2m_to_mask(_t) & P2M_CHANGEABLE_TYPES)
+#define p2m_is_ioreq(_t) (p2m_to_mask(_t) & P2M_IOREQ_TYPES)
 #define p2m_is_pod(_t) (p2m_to_mask(_t) & P2M_POD_TYPES)
 #define p2m_is_grant(_t) (p2m_to_mask(_t) & P2M_GRANT_TYPES)
 /* Grant types are *not* considered valid, because they can be
@@ -178,6 +182,8 @@ typedef unsigned int p2m_query_t;
 
 #define p2m_allows_invalid_mfn(t) (p2m_to_mask(t) & P2M_INVALID_MFN_TYPES)
 
+#define p2m_check_changeable(t) (p2m_is_changeable(t) && !p2m_is_ioreq(t))
+
 typedef enum {
     p2m_host,
     p2m_nested,
@@ -349,6 +355,7 @@ struct p2m_domain {
           * are to be emulated by an ioreq server.
           */
          unsigned int flags;
+         long entry_count;
      } ioreq;
 };
 
-- 
1.9.1


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[PATCH v8 5/5] x86/ioreq server: Synchronously reset outstanding p2m_ioreq_server entries when an ioreq server unmaps.

[Yu Zhang]

After an ioreq server has unmapped, the remaining p2m_ioreq_server
entries need to be reset back to p2m_ram_rw. This patch does this
synchronously by iterating the p2m table.

The synchronous resetting is necessary because we need to guarantee
the p2m table is clean before another ioreq server is mapped. And
since the sweeping of p2m table could be time consuming, it is done
with hypercall continuation.

Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com>
---
Cc: Paul Durrant <paul.durrant@citrix.com>
Cc: Jan Beulich <jbeulich@suse.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: George Dunlap <george.dunlap@eu.citrix.com>

changes in v2: 
  - According to comments from Jan and Andrew: do not use the
    HVMOP type hypercall continuation method. Instead, adding
    an opaque in xen_dm_op_map_mem_type_to_ioreq_server to
    store the gfn.
  - According to comments from Jan: change routine's comments
    and name of parameters of p2m_finish_type_change().

changes in v1: 
  - This patch is splitted from patch 4 of last version.
  - According to comments from Jan: update the gfn_start for 
    when use hypercall continuation to reset the p2m type.
  - According to comments from Jan: use min() to compare gfn_end
    and max mapped pfn in p2m_finish_type_change()
---
 xen/arch/x86/hvm/dm.c     | 41 ++++++++++++++++++++++++++++++++++++++---
 xen/arch/x86/mm/p2m.c     | 29 +++++++++++++++++++++++++++++
 xen/include/asm-x86/p2m.h |  7 +++++++
 3 files changed, 74 insertions(+), 3 deletions(-)

diff --git a/xen/arch/x86/hvm/dm.c b/xen/arch/x86/hvm/dm.c
index 1619feb..9e1e27b 100644
--- a/xen/arch/x86/hvm/dm.c
+++ b/xen/arch/x86/hvm/dm.c
@@ -385,16 +385,51 @@ static int dm_op(domid_t domid,
 
     case XEN_DMOP_map_mem_type_to_ioreq_server:
     {
-        const struct xen_dm_op_map_mem_type_to_ioreq_server *data =
+        struct xen_dm_op_map_mem_type_to_ioreq_server *data =
             &op.u.map_mem_type_to_ioreq_server;
+        unsigned long first_gfn = data->opaque;
+        unsigned long last_gfn;
+
+        const_op = false;
 
         rc = -EOPNOTSUPP;
         /* Only support for HAP enabled hvm. */
         if ( !hap_enabled(d) )
             break;
 
-        rc = hvm_map_mem_type_to_ioreq_server(d, data->id,
-                                              data->type, data->flags);
+        if ( first_gfn == 0 )
+            rc = hvm_map_mem_type_to_ioreq_server(d, data->id,
+                                                  data->type, data->flags);
+        /*
+         * Iterate p2m table when an ioreq server unmaps from p2m_ioreq_server,
+         * and reset the remaining p2m_ioreq_server entries back to p2m_ram_rw.
+         */
+        if ( (first_gfn > 0) || (data->flags == 0 && rc == 0) )
+        {
+            struct p2m_domain *p2m = p2m_get_hostp2m(d);
+
+            while ( read_atomic(&p2m->ioreq.entry_count) &&
+                    first_gfn <= p2m->max_mapped_pfn )
+            {
+                /* Iterate p2m table for 256 gfns each time. */
+                last_gfn = first_gfn + 0xff;
+
+                p2m_finish_type_change(d, first_gfn, last_gfn,
+                                       p2m_ioreq_server, p2m_ram_rw);
+
+                first_gfn = last_gfn + 1;
+
+                /* Check for continuation if it's not the last iteration. */
+                if ( first_gfn <= p2m->max_mapped_pfn &&
+                     hypercall_preempt_check() )
+                {
+                    rc = -ERESTART;
+                    data->opaque = first_gfn;
+                    break;
+                }
+            }
+        }
+
         break;
     }
 
diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c
index 87f274d..03bc309 100644
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -1038,6 +1038,35 @@ void p2m_change_type_range(struct domain *d,
     p2m_unlock(p2m);
 }
 
+/* Synchronously modify the p2m type for a range of gfns from ot to nt. */
+void p2m_finish_type_change(struct domain *d,
+                            unsigned long first_gfn, unsigned long last_gfn,
+                            p2m_type_t ot, p2m_type_t nt)
+{
+    struct p2m_domain *p2m = p2m_get_hostp2m(d);
+    p2m_type_t t;
+    unsigned long gfn = first_gfn;
+
+    ASSERT(first_gfn <= last_gfn);
+    ASSERT(ot != nt);
+    ASSERT(p2m_is_changeable(ot) && p2m_is_changeable(nt));
+
+    p2m_lock(p2m);
+
+    last_gfn = min(last_gfn, p2m->max_mapped_pfn);
+    while ( gfn <= last_gfn )
+    {
+        get_gfn_query_unlocked(d, gfn, &t);
+
+        if ( t == ot )
+            p2m_change_type_one(d, gfn, t, nt);
+
+        gfn++;
+    }
+
+    p2m_unlock(p2m);
+}
+
 /*
  * Returns:
  *    0              for success
diff --git a/xen/include/asm-x86/p2m.h b/xen/include/asm-x86/p2m.h
index 395f125..3d665e8 100644
--- a/xen/include/asm-x86/p2m.h
+++ b/xen/include/asm-x86/p2m.h
@@ -611,6 +611,13 @@ void p2m_change_type_range(struct domain *d,
 int p2m_change_type_one(struct domain *d, unsigned long gfn,
                         p2m_type_t ot, p2m_type_t nt);
 
+/* Synchronously change the p2m type for a range of gfns:
+ * [first_gfn ... last_gfn]. */
+void p2m_finish_type_change(struct domain *d,
+                            unsigned long first_gfn,
+                            unsigned long last_gfn,
+                            p2m_type_t ot, p2m_type_t nt);
+
 /* Report a change affecting memory types. */
 void p2m_memory_type_changed(struct domain *d);
 
-- 
1.9.1


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Re: [PATCH v8 1/5] x86/ioreq server: Release the p2m lock after mmio is handled.

[Jan Beulich]

>>> On 18.03.17 at 11:53, <yu.c.zhang@linux.intel.com> wrote:
> --- a/xen/arch/x86/hvm/hvm.c
> +++ b/xen/arch/x86/hvm/hvm.c
> @@ -1870,18 +1870,14 @@ int hvm_hap_nested_page_fault(paddr_t gpa, unsigned long gla,
>           (npfec.write_access &&
>            (p2m_is_discard_write(p2mt) || (p2mt == p2m_ioreq_server))) )
>      {
> -        __put_gfn(p2m, gfn);
> -        if ( ap2m_active )
> -            __put_gfn(hostp2m, gfn);
> -
>          rc = 0;
>          if ( unlikely(is_pvh_domain(currd)) )
> -            goto out;
> +            goto out_put_gfn;

Did you forget to re-base onto staging before you've sent this?
is_pvh_domain() was gone before your submission already. When
re-basing, feel free to also drop the dead "rc = 0;" line.

Jan


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Re: [PATCH v8 1/5] x86/ioreq server: Release the p2m lock after mmio is handled.

[Yu Zhang]

On 3/21/2017 1:03 AM, Jan Beulich wrote:
>>>> On 18.03.17 at 11:53, <yu.c.zhang@linux.intel.com> wrote:
>> --- a/xen/arch/x86/hvm/hvm.c
>> +++ b/xen/arch/x86/hvm/hvm.c
>> @@ -1870,18 +1870,14 @@ int hvm_hap_nested_page_fault(paddr_t gpa, unsigned long gla,
>>            (npfec.write_access &&
>>             (p2m_is_discard_write(p2mt) || (p2mt == p2m_ioreq_server))) )
>>       {
>> -        __put_gfn(p2m, gfn);
>> -        if ( ap2m_active )
>> -            __put_gfn(hostp2m, gfn);
>> -
>>           rc = 0;
>>           if ( unlikely(is_pvh_domain(currd)) )
>> -            goto out;
>> +            goto out_put_gfn;
> Did you forget to re-base onto staging before you've sent this?
> is_pvh_domain() was gone before your submission already. When
> re-basing, feel free to also drop the dead "rc = 0;" line.

Oops...
I did a rebase days ago, but did not send the patch directly. There were 
some XenGT test performed based on these patch.
Sorry, I should have a check.  Will resend the patch. :)

B.R.
Yu
> Jan
>
>


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Re: [PATCH v8 1/5] x86/ioreq server: Release the p2m lock after mmio is handled.

[Yu Zhang]

On 3/21/2017 9:18 AM, Yu Zhang wrote:
>
>
> On 3/21/2017 1:03 AM, Jan Beulich wrote:
>>>>> On 18.03.17 at 11:53, <yu.c.zhang@linux.intel.com> wrote:
>>> --- a/xen/arch/x86/hvm/hvm.c
>>> +++ b/xen/arch/x86/hvm/hvm.c
>>> @@ -1870,18 +1870,14 @@ int hvm_hap_nested_page_fault(paddr_t gpa, 
>>> unsigned long gla,
>>>            (npfec.write_access &&
>>>             (p2m_is_discard_write(p2mt) || (p2mt == 
>>> p2m_ioreq_server))) )
>>>       {
>>> -        __put_gfn(p2m, gfn);
>>> -        if ( ap2m_active )
>>> -            __put_gfn(hostp2m, gfn);
>>> -
>>>           rc = 0;
>>>           if ( unlikely(is_pvh_domain(currd)) )
>>> -            goto out;
>>> +            goto out_put_gfn;
>> Did you forget to re-base onto staging before you've sent this?
>> is_pvh_domain() was gone before your submission already. When
>> re-basing, feel free to also drop the dead "rc = 0;" line.
>
> Oops...
> I did a rebase days ago, but did not send the patch directly. There 
> were some XenGT test performed based on these patch.
> Sorry, I should have a check.  Will resend the patch. :)
>

BTW, since there's another change - "drop the rc = 0", I'd like to send 
the new patchset with a new version nubmer. :-)

Yu
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xen.org
> https://lists.xen.org/xen-devel


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