[Xen-changelog] [xen master] x86/emul: Simplfy emulation state setup

[patchbot@xxxxxxx]

commit 2191599bacb7b748ad9e310ea0ff74ae2ac9acc4
Author:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
AuthorDate: Wed Nov 23 13:34:52 2016 +0000
Commit:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CommitDate: Fri Dec 2 17:23:01 2016 +0000

    x86/emul: Simplfy emulation state setup
    
    The current code to set up emulation state is ad-hoc and error prone.
    
     * Consistently zero all emulation state structures.
     * Avoid explicitly initialising some state to 0.
     * Explicitly identify all input and output state in x86_emulate_ctxt.  This
       involves rearanging some fields.
     * Have x86_decode() explicitly initalise all output state at its start.
    
    While making the above changes, two minor tweaks:
    
     * Move the calculation of hvmemul_ctxt->ctxt.swint_emulate from
       _hvm_emulate_one() to hvm_emulate_init_once().  It doesn't need
       recalculating for each instruction.
     * Change force_writeback to being a boolean, to match its use.
    
    Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Acked-by: Tim Deegan <tim@xxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Paul Durrant <paul.durrant@xxxxxxxxxx>
---
 xen/arch/x86/hvm/emulate.c             | 28 +++++++++++++++-------------
 xen/arch/x86/mm.c                      | 14 ++++++++------
 xen/arch/x86/mm/shadow/common.c        |  4 ++--
 xen/arch/x86/x86_emulate/x86_emulate.c |  1 +
 xen/arch/x86/x86_emulate/x86_emulate.h | 32 ++++++++++++++++++++++----------
 5 files changed, 48 insertions(+), 31 deletions(-)

diff --git a/xen/arch/x86/hvm/emulate.c b/xen/arch/x86/hvm/emulate.c
index f1f6e2f..3efeead 100644
--- a/xen/arch/x86/hvm/emulate.c
+++ b/xen/arch/x86/hvm/emulate.c
@@ -1770,13 +1770,6 @@ static int _hvm_emulate_one(struct hvm_emulate_ctxt 
*hvmemul_ctxt,
 
     vio->mmio_retry = 0;
 
-    if ( cpu_has_vmx )
-        hvmemul_ctxt->ctxt.swint_emulate = x86_swint_emulate_none;
-    else if ( cpu_has_svm_nrips )
-        hvmemul_ctxt->ctxt.swint_emulate = x86_swint_emulate_icebp;
-    else
-        hvmemul_ctxt->ctxt.swint_emulate = x86_swint_emulate_all;
-
     rc = x86_emulate(&hvmemul_ctxt->ctxt, ops);
 
     if ( rc == X86EMUL_OKAY && vio->mmio_retry )
@@ -1947,14 +1940,23 @@ void hvm_emulate_init_once(
     struct hvm_emulate_ctxt *hvmemul_ctxt,
     struct cpu_user_regs *regs)
 {
-    hvmemul_ctxt->intr_shadow = hvm_funcs.get_interrupt_shadow(current);
-    hvmemul_ctxt->ctxt.regs = regs;
-    hvmemul_ctxt->ctxt.force_writeback = 1;
-    hvmemul_ctxt->seg_reg_accessed = 0;
-    hvmemul_ctxt->seg_reg_dirty = 0;
-    hvmemul_ctxt->set_context = 0;
+    struct vcpu *curr = current;
+
+    memset(hvmemul_ctxt, 0, sizeof(*hvmemul_ctxt));
+
+    hvmemul_ctxt->intr_shadow = hvm_funcs.get_interrupt_shadow(curr);
     hvmemul_get_seg_reg(x86_seg_cs, hvmemul_ctxt);
     hvmemul_get_seg_reg(x86_seg_ss, hvmemul_ctxt);
+
+    hvmemul_ctxt->ctxt.regs = regs;
+    hvmemul_ctxt->ctxt.force_writeback = true;
+
+    if ( cpu_has_vmx )
+        hvmemul_ctxt->ctxt.swint_emulate = x86_swint_emulate_none;
+    else if ( cpu_has_svm_nrips )
+        hvmemul_ctxt->ctxt.swint_emulate = x86_swint_emulate_icebp;
+    else
+        hvmemul_ctxt->ctxt.swint_emulate = x86_swint_emulate_all;
 }
 
 void hvm_emulate_init_per_insn(
diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
index 5b0e9f3..d365f59 100644
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -5337,7 +5337,14 @@ int ptwr_do_page_fault(struct vcpu *v, unsigned long 
addr,
     struct domain *d = v->domain;
     struct page_info *page;
     l1_pgentry_t      pte;
-    struct ptwr_emulate_ctxt ptwr_ctxt;
+    struct ptwr_emulate_ctxt ptwr_ctxt = {
+        .ctxt = {
+            .regs = regs,
+            .addr_size = is_pv_32bit_domain(d) ? 32 : BITS_PER_LONG,
+            .sp_size   = is_pv_32bit_domain(d) ? 32 : BITS_PER_LONG,
+            .swint_emulate = x86_swint_emulate_none,
+        },
+    };
     int rc;
 
     /* Attempt to read the PTE that maps the VA being accessed. */
@@ -5363,11 +5370,6 @@ int ptwr_do_page_fault(struct vcpu *v, unsigned long 
addr,
         goto bail;
     }
 
-    ptwr_ctxt.ctxt.regs = regs;
-    ptwr_ctxt.ctxt.force_writeback = 0;
-    ptwr_ctxt.ctxt.addr_size = ptwr_ctxt.ctxt.sp_size =
-        is_pv_32bit_domain(d) ? 32 : BITS_PER_LONG;
-    ptwr_ctxt.ctxt.swint_emulate = x86_swint_emulate_none;
     ptwr_ctxt.cr2 = addr;
     ptwr_ctxt.pte = pte;
 
diff --git a/xen/arch/x86/mm/shadow/common.c b/xen/arch/x86/mm/shadow/common.c
index 1623a07..392bcbe 100644
--- a/xen/arch/x86/mm/shadow/common.c
+++ b/xen/arch/x86/mm/shadow/common.c
@@ -385,8 +385,9 @@ const struct x86_emulate_ops *shadow_init_emulation(
     struct vcpu *v = current;
     unsigned long addr;
 
+    memset(sh_ctxt, 0, sizeof(*sh_ctxt));
+
     sh_ctxt->ctxt.regs = regs;
-    sh_ctxt->ctxt.force_writeback = 0;
     sh_ctxt->ctxt.swint_emulate = x86_swint_emulate_none;
 
     if ( is_pv_vcpu(v) )
@@ -396,7 +397,6 @@ const struct x86_emulate_ops *shadow_init_emulation(
     }
 
     /* Segment cache initialisation. Primed with CS. */
-    sh_ctxt->valid_seg_regs = 0;
     creg = hvm_get_seg_reg(x86_seg_cs, sh_ctxt);
 
     /* Work out the emulation mode. */
diff --git a/xen/arch/x86/x86_emulate/x86_emulate.c 
b/xen/arch/x86/x86_emulate/x86_emulate.c
index d82e85d..532bd32 100644
--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -1904,6 +1904,7 @@ x86_decode(
     state->regs = ctxt->regs;
     state->eip = ctxt->regs->eip;
 
+    /* Initialise output state in x86_emulate_ctxt */
     ctxt->retire.byte = 0;
 
     op_bytes = def_op_bytes = ad_bytes = def_ad_bytes = ctxt->addr_size/8;
diff --git a/xen/arch/x86/x86_emulate/x86_emulate.h 
b/xen/arch/x86/x86_emulate/x86_emulate.h
index ec824ce..ab566c0 100644
--- a/xen/arch/x86/x86_emulate/x86_emulate.h
+++ b/xen/arch/x86/x86_emulate/x86_emulate.h
@@ -410,6 +410,23 @@ struct cpu_user_regs;
 
 struct x86_emulate_ctxt
 {
+    /*
+     * Input-only state:
+     */
+
+    /* Software event injection support. */
+    enum x86_swint_emulation swint_emulate;
+
+    /* Set this if writes may have side effects. */
+    bool force_writeback;
+
+    /* Caller data that can be used by x86_emulate_ops' routines. */
+    void *data;
+
+    /*
+     * Input/output state:
+     */
+
     /* Register state before/after emulation. */
     struct cpu_user_regs *regs;
 
@@ -419,14 +436,12 @@ struct x86_emulate_ctxt
     /* Stack pointer width in bits (16, 32 or 64). */
     unsigned int sp_size;
 
-    /* Canonical opcode (see below). */
-    unsigned int opcode;
-
-    /* Software event injection support. */
-    enum x86_swint_emulation swint_emulate;
+    /*
+     * Output-only state:
+     */
 
-    /* Set this if writes may have side effects. */
-    uint8_t force_writeback;
+    /* Canonical opcode (see below) (valid only on X86EMUL_OKAY). */
+    unsigned int opcode;
 
     /* Retirement state, set by the emulator (valid only on X86EMUL_OKAY). */
     union {
@@ -437,9 +452,6 @@ struct x86_emulate_ctxt
         } flags;
         uint8_t byte;
     } retire;
-
-    /* Caller data that can be used by x86_emulate_ops' routines. */
-    void *data;
 };
 
 /*
--
generated by git-patchbot for /home/xen/git/xen.git#master

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