Mailing List Archive

[xen staging] x86/svm: Don't shadow variables in svm_vmexit_handler()
commit 115c05a5f9b78ee596895065ee4a28c106096771
Author: Andrew Cooper <andrew.cooper3@citrix.com>
AuthorDate: Mon Nov 25 13:29:20 2019 +0000
Commit: Andrew Cooper <andrew.cooper3@citrix.com>
CommitDate: Thu Dec 5 13:19:28 2019 +0000

x86/svm: Don't shadow variables in svm_vmexit_handler()

The local variable eventinj is set to the value of vmcb->exitintinfo which is
confusing considering that it isn't vmcb->eventinj. The variable isn't
necessary to begin with, so drop it to avoid confusion.

A local rc variable is shadowed in the CPUID, #DB and #BP handlers.

There is a mix of spelling of inst_len and insn_len, all of which are
logically the same value. Consolidate on insn_len which also matches the name
of the emulation functions for obtaining instruction lengths, and avoid
shadowing it in the CPUID and TASK_SWITCH handlers.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
---
xen/arch/x86/hvm/svm/svm.c | 63 ++++++++++++++++++++--------------------------
1 file changed, 27 insertions(+), 36 deletions(-)

diff --git a/xen/arch/x86/hvm/svm/svm.c b/xen/arch/x86/hvm/svm/svm.c
index 7cb235a667..a0be4da6a1 100644
--- a/xen/arch/x86/hvm/svm/svm.c
+++ b/xen/arch/x86/hvm/svm/svm.c
@@ -2480,8 +2480,7 @@ void svm_vmexit_handler(struct cpu_user_regs *regs)
uint64_t exit_reason;
struct vcpu *v = current;
struct vmcb_struct *vmcb = v->arch.hvm.svm.vmcb;
- eventinj_t eventinj;
- int inst_len, rc;
+ int insn_len, rc;
vintr_t intr;
bool_t vcpu_guestmode = 0;
struct vlapic *vlapic = vcpu_vlapic(v);
@@ -2603,11 +2602,10 @@ void svm_vmexit_handler(struct cpu_user_regs *regs)
vmcb->cleanbits.bytes = cpu_has_svm_cleanbits ? ~0u : 0u;

/* Event delivery caused this intercept? Queue for redelivery. */
- eventinj = vmcb->exitintinfo;
- if ( unlikely(eventinj.fields.v) &&
- hvm_event_needs_reinjection(eventinj.fields.type,
- eventinj.fields.vector) )
- vmcb->eventinj = eventinj;
+ if ( unlikely(vmcb->exitintinfo.fields.v) &&
+ hvm_event_needs_reinjection(vmcb->exitintinfo.fields.type,
+ vmcb->exitintinfo.fields.vector) )
+ vmcb->eventinj = vmcb->exitintinfo;

switch ( exit_reason )
{
@@ -2630,63 +2628,60 @@ void svm_vmexit_handler(struct cpu_user_regs *regs)
case VMEXIT_EXCEPTION_DB:
if ( !v->domain->debugger_attached )
{
- int rc;
unsigned int trap_type;

if ( likely(exit_reason != VMEXIT_ICEBP) )
{
trap_type = X86_EVENTTYPE_HW_EXCEPTION;
- inst_len = 0;
+ insn_len = 0;
}
else
{
trap_type = X86_EVENTTYPE_PRI_SW_EXCEPTION;
- inst_len = svm_get_insn_len(v, INSTR_ICEBP);
+ insn_len = svm_get_insn_len(v, INSTR_ICEBP);

- if ( !inst_len )
+ if ( !insn_len )
break;
}

rc = hvm_monitor_debug(regs->rip,
HVM_MONITOR_DEBUG_EXCEPTION,
- trap_type, inst_len);
+ trap_type, insn_len);
if ( rc < 0 )
goto unexpected_exit_type;
if ( !rc )
hvm_inject_exception(TRAP_debug,
- trap_type, inst_len, X86_EVENT_NO_EC);
+ trap_type, insn_len, X86_EVENT_NO_EC);
}
else
domain_pause_for_debugger();
break;

case VMEXIT_EXCEPTION_BP:
- inst_len = svm_get_insn_len(v, INSTR_INT3);
+ insn_len = svm_get_insn_len(v, INSTR_INT3);

- if ( inst_len == 0 )
+ if ( insn_len == 0 )
break;

if ( v->domain->debugger_attached )
{
/* AMD Vol2, 15.11: INT3, INTO, BOUND intercepts do not update RIP. */
- __update_guest_eip(regs, inst_len);
+ __update_guest_eip(regs, insn_len);
current->arch.gdbsx_vcpu_event = TRAP_int3;
domain_pause_for_debugger();
}
else
{
- int rc;
-
rc = hvm_monitor_debug(regs->rip,
HVM_MONITOR_SOFTWARE_BREAKPOINT,
X86_EVENTTYPE_SW_EXCEPTION,
- inst_len);
+ insn_len);
if ( rc < 0 )
goto unexpected_exit_type;
if ( !rc )
hvm_inject_exception(TRAP_int3,
X86_EVENTTYPE_SW_EXCEPTION,
- inst_len, X86_EVENT_NO_EC);
+ insn_len, X86_EVENT_NO_EC);
}
break;

@@ -2757,7 +2752,7 @@ void svm_vmexit_handler(struct cpu_user_regs *regs)

case VMEXIT_TASK_SWITCH: {
enum hvm_task_switch_reason reason;
- int32_t errcode = -1, insn_len = -1;
+ int32_t errcode = -1;

/*
* All TASK_SWITCH intercepts have fault-like semantics. NRIP is
@@ -2769,6 +2764,7 @@ void svm_vmexit_handler(struct cpu_user_regs *regs)
* to distinguish interrupts/exceptions from instruction based
* switches.
*/
+ insn_len = -1;
if ( vmcb->exitintinfo.fields.v )
{
switch ( vmcb->exitintinfo.fields.type )
@@ -2818,22 +2814,17 @@ void svm_vmexit_handler(struct cpu_user_regs *regs)
}

case VMEXIT_CPUID:
- {
- unsigned int inst_len = svm_get_insn_len(v, INSTR_CPUID);
- int rc = 0;
-
- if ( inst_len == 0 )
+ if ( (insn_len = svm_get_insn_len(v, INSTR_CPUID)) == 0 )
break;

- rc = hvm_vmexit_cpuid(regs, inst_len);
+ rc = hvm_vmexit_cpuid(regs, insn_len);

if ( rc < 0 )
goto unexpected_exit_type;
if ( !rc )
- __update_guest_eip(regs, inst_len); /* Safe: CPUID */
-
+ __update_guest_eip(regs, insn_len);
break;
- }
+
case VMEXIT_HLT:
svm_vmexit_do_hlt(vmcb, regs);
break;
@@ -2875,20 +2866,20 @@ void svm_vmexit_handler(struct cpu_user_regs *regs)
hvm_inject_hw_exception(TRAP_invalid_op, X86_EVENT_NO_EC);
break;
}
- if ( (inst_len = svm_get_insn_len(v, INSTR_INVLPGA)) == 0 )
+ if ( (insn_len = svm_get_insn_len(v, INSTR_INVLPGA)) == 0 )
break;
svm_invlpga_intercept(v, regs->rax, regs->ecx);
- __update_guest_eip(regs, inst_len);
+ __update_guest_eip(regs, insn_len);
break;

case VMEXIT_VMMCALL:
- if ( (inst_len = svm_get_insn_len(v, INSTR_VMCALL)) == 0 )
+ if ( (insn_len = svm_get_insn_len(v, INSTR_VMCALL)) == 0 )
break;
BUG_ON(vcpu_guestmode);
HVMTRACE_1D(VMMCALL, regs->eax);

if ( hvm_hypercall(regs) == HVM_HCALL_completed )
- __update_guest_eip(regs, inst_len);
+ __update_guest_eip(regs, insn_len);
break;

case VMEXIT_DR0_READ ... VMEXIT_DR7_READ:
@@ -2936,9 +2927,9 @@ void svm_vmexit_handler(struct cpu_user_regs *regs)
case VMEXIT_XSETBV:
if ( vmcb_get_cpl(vmcb) )
hvm_inject_hw_exception(TRAP_gp_fault, 0);
- else if ( (inst_len = svm_get_insn_len(v, INSTR_XSETBV)) &&
+ else if ( (insn_len = svm_get_insn_len(v, INSTR_XSETBV)) &&
hvm_handle_xsetbv(regs->ecx, msr_fold(regs)) == X86EMUL_OKAY )
- __update_guest_eip(regs, inst_len);
+ __update_guest_eip(regs, insn_len);
break;

case VMEXIT_NPF:
--
generated by git-patchbot for /home/xen/git/xen.git#staging

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