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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-changelog] [xen staging] x86/hvm: make hvmemul_virtual_to_linear()'s reps parameter optional
commit 3bfe102c16b0590d4f885250e82a2ef623867cf4
Author: Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Tue Jul 16 09:09:44 2019 +0200
Commit: Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Tue Jul 16 09:09:44 2019 +0200
x86/hvm: make hvmemul_virtual_to_linear()'s reps parameter optional
A majority of callers wants just a single iteration handled. Allow to
express this by passing in a NULL pointer, instead of setting up a local
variable just to hold the "1" to pass in here.
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
Reviewed-by: Alexandru Isaila <aisaila@xxxxxxxxxxxxxxx>
Reviewed-by: Paul Durrant <paul.durrant@xxxxxxxxxx>
---
xen/arch/x86/hvm/emulate.c | 84 ++++++++++++++++++++++++++--------------------
1 file changed, 47 insertions(+), 37 deletions(-)
diff --git a/xen/arch/x86/hvm/emulate.c b/xen/arch/x86/hvm/emulate.c
index 8659c89862..d75d3e6fd6 100644
--- a/xen/arch/x86/hvm/emulate.c
+++ b/xen/arch/x86/hvm/emulate.c
@@ -788,14 +788,14 @@ static int hvmemul_virtual_to_linear(
enum x86_segment seg,
unsigned long offset,
unsigned int bytes_per_rep,
- unsigned long *reps,
+ unsigned long *reps_p,
enum hvm_access_type access_type,
struct hvm_emulate_ctxt *hvmemul_ctxt,
unsigned long *linear)
{
struct segment_register *reg;
int okay;
- unsigned long max_reps = 4096;
+ unsigned long reps = 1;
if ( seg == x86_seg_none )
{
@@ -803,62 +803,72 @@ static int hvmemul_virtual_to_linear(
return X86EMUL_OKAY;
}
- /*
- * If introspection has been enabled for this domain, and we're emulating
- * becase a vm_reply asked us to (i.e. not doing regular IO) reps should
- * be at most 1, since optimization might otherwise cause a single
- * vm_event being triggered for repeated writes to a whole page.
- */
- if ( unlikely(current->domain->arch.mem_access_emulate_each_rep) &&
- current->arch.vm_event->emulate_flags != 0 )
- max_reps = 1;
+ if ( reps_p )
+ {
+ unsigned long max_reps = 4096;
- /*
- * Clip repetitions to avoid overflow when multiplying by @bytes_per_rep.
- * The chosen maximum is very conservative but it's what we use in
- * hvmemul_linear_to_phys() so there is no point in using a larger value.
- */
- *reps = min_t(unsigned long, *reps, max_reps);
+ /*
+ * If introspection has been enabled for this domain, and we're
+ * emulating because a vm_reply asked us to (i.e. not doing regular IO)
+ * reps should be at most 1, since optimization might otherwise cause a
+ * single vm_event being triggered for repeated writes to a whole page.
+ */
+ if ( unlikely(current->domain->arch.mem_access_emulate_each_rep) &&
+ current->arch.vm_event->emulate_flags != 0 )
+ max_reps = 1;
+
+ /*
+ * Clip repetitions to avoid overflow when multiplying by
+ * @bytes_per_rep. The chosen maximum is very conservative but it's
+ * what we use in hvmemul_linear_to_phys() so there is no point in
+ * using a larger value.
+ */
+ reps = *reps_p = min_t(unsigned long, *reps_p, max_reps);
+ }
reg = hvmemul_get_seg_reg(seg, hvmemul_ctxt);
if ( IS_ERR(reg) )
return -PTR_ERR(reg);
- if ( (hvmemul_ctxt->ctxt.regs->eflags & X86_EFLAGS_DF) && (*reps > 1) )
+ if ( (hvmemul_ctxt->ctxt.regs->eflags & X86_EFLAGS_DF) && (reps > 1) )
{
/*
* x86_emulate() clips the repetition count to ensure we don't wrap
* the effective-address index register. Hence this assertion holds.
*/
- ASSERT(offset >= ((*reps - 1) * bytes_per_rep));
+ ASSERT(offset >= ((reps - 1) * bytes_per_rep));
okay = hvm_virtual_to_linear_addr(
- seg, reg, offset - (*reps - 1) * bytes_per_rep,
- *reps * bytes_per_rep, access_type,
+ seg, reg, offset - (reps - 1) * bytes_per_rep,
+ reps * bytes_per_rep, access_type,
hvmemul_get_seg_reg(x86_seg_cs, hvmemul_ctxt), linear);
- *linear += (*reps - 1) * bytes_per_rep;
+ *linear += (reps - 1) * bytes_per_rep;
if ( hvmemul_ctxt->ctxt.addr_size != 64 )
*linear = (uint32_t)*linear;
}
else
{
okay = hvm_virtual_to_linear_addr(
- seg, reg, offset, *reps * bytes_per_rep, access_type,
+ seg, reg, offset, reps * bytes_per_rep, access_type,
hvmemul_get_seg_reg(x86_seg_cs, hvmemul_ctxt), linear);
}
if ( okay )
return X86EMUL_OKAY;
- /* If this is a string operation, emulate each iteration separately. */
- if ( *reps != 1 )
- return X86EMUL_UNHANDLEABLE;
+ if ( reps_p )
+ {
+ /* If this is a string operation, emulate each iteration separately. */
+ if ( reps != 1 )
+ return X86EMUL_UNHANDLEABLE;
+
+ *reps_p = 0;
+ }
/*
* Leave exception injection to the caller for non-user segments: We
* neither know the exact error code to be used, nor can we easily
* determine the kind of exception (#GP or #TS) in that case.
*/
- *reps = 0;
if ( is_x86_user_segment(seg) )
x86_emul_hw_exception((seg == x86_seg_ss)
? TRAP_stack_error
@@ -1201,7 +1211,7 @@ static int __hvmemul_read(
enum hvm_access_type access_type,
struct hvm_emulate_ctxt *hvmemul_ctxt)
{
- unsigned long addr, reps = 1;
+ unsigned long addr;
uint32_t pfec = PFEC_page_present;
int rc;
@@ -1213,7 +1223,7 @@ static int __hvmemul_read(
pfec |= PFEC_insn_fetch;
rc = hvmemul_virtual_to_linear(
- seg, offset, bytes, &reps, access_type, hvmemul_ctxt, &addr);
+ seg, offset, bytes, NULL, access_type, hvmemul_ctxt, &addr);
if ( rc != X86EMUL_OKAY || !bytes )
return rc;
@@ -1294,7 +1304,7 @@ static int hvmemul_write(
{
struct hvm_emulate_ctxt *hvmemul_ctxt =
container_of(ctxt, struct hvm_emulate_ctxt, ctxt);
- unsigned long addr, reps = 1;
+ unsigned long addr;
uint32_t pfec = PFEC_page_present | PFEC_write_access;
int rc;
void *mapping = NULL;
@@ -1305,7 +1315,7 @@ static int hvmemul_write(
pfec |= PFEC_user_mode;
rc = hvmemul_virtual_to_linear(
- seg, offset, bytes, &reps, hvm_access_write, hvmemul_ctxt, &addr);
+ seg, offset, bytes, NULL, hvm_access_write, hvmemul_ctxt, &addr);
if ( rc != X86EMUL_OKAY || !bytes )
return rc;
@@ -1336,13 +1346,13 @@ static int hvmemul_rmw(
{
struct hvm_emulate_ctxt *hvmemul_ctxt =
container_of(ctxt, struct hvm_emulate_ctxt, ctxt);
- unsigned long addr, reps = 1;
+ unsigned long addr;
uint32_t pfec = PFEC_page_present | PFEC_write_access;
int rc;
void *mapping = NULL;
rc = hvmemul_virtual_to_linear(
- seg, offset, bytes, &reps, hvm_access_write, hvmemul_ctxt, &addr);
+ seg, offset, bytes, NULL, hvm_access_write, hvmemul_ctxt, &addr);
if ( rc != X86EMUL_OKAY || !bytes )
return rc;
@@ -1491,14 +1501,14 @@ static int hvmemul_cmpxchg(
struct hvm_emulate_ctxt *hvmemul_ctxt =
container_of(ctxt, struct hvm_emulate_ctxt, ctxt);
struct vcpu *curr = current;
- unsigned long addr, reps = 1;
+ unsigned long addr;
uint32_t pfec = PFEC_page_present | PFEC_write_access;
struct hvm_vcpu_io *vio = &curr->arch.hvm.hvm_io;
int rc;
void *mapping = NULL;
rc = hvmemul_virtual_to_linear(
- seg, offset, bytes, &reps, hvm_access_write, hvmemul_ctxt, &addr);
+ seg, offset, bytes, NULL, hvm_access_write, hvmemul_ctxt, &addr);
if ( rc != X86EMUL_OKAY )
return rc;
@@ -2292,11 +2302,11 @@ static int hvmemul_invlpg(
{
struct hvm_emulate_ctxt *hvmemul_ctxt =
container_of(ctxt, struct hvm_emulate_ctxt, ctxt);
- unsigned long addr, reps = 1;
+ unsigned long addr;
int rc;
rc = hvmemul_virtual_to_linear(
- seg, offset, 1, &reps, hvm_access_none, hvmemul_ctxt, &addr);
+ seg, offset, 1, NULL, hvm_access_none, hvmemul_ctxt, &addr);
if ( rc == X86EMUL_EXCEPTION )
{
--
generated by git-patchbot for /home/xen/git/xen.git#staging
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