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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH 5/8] x86/hvm: Don't raise #GP behind the emulators back for MSR accesses
The current hvm_msr_{read,write}_intercept() infrastructure calls
hvm_inject_hw_exception() directly to latch a fault, and returns
X86EMUL_EXCEPTION to its caller.
This behaviour is problematic for the hvmemul_{read,write}_msr() paths, as the
fault is raised behind the back of the x86 emulator.
Alter the behaviour so hvm_msr_{read,write}_intercept() simply returns
X86EMUL_EXCEPTION, leaving the callers to actually inject the #GP fault.
Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Paul Durrant <paul.durrant@xxxxxxxxxx>
CC: Jun Nakajima <jun.nakajima@xxxxxxxxx>
CC: Kevin Tian <kevin.tian@xxxxxxxxx>
CC: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
CC: Suravee Suthikulpanit <suravee.suthikulpanit@xxxxxxx>
---
xen/arch/x86/hvm/emulate.c | 14 ++++++++++++--
xen/arch/x86/hvm/hvm.c | 8 +++++---
xen/arch/x86/hvm/svm/svm.c | 4 ++--
xen/arch/x86/hvm/vmx/vmx.c | 32 +++++++++++++++++++++-----------
xen/arch/x86/hvm/vmx/vvmx.c | 19 ++++++++++++++-----
xen/include/asm-x86/hvm/support.h | 11 ++++++++---
6 files changed, 62 insertions(+), 26 deletions(-)
diff --git a/xen/arch/x86/hvm/emulate.c b/xen/arch/x86/hvm/emulate.c
index d0a043b..b182d57 100644
--- a/xen/arch/x86/hvm/emulate.c
+++ b/xen/arch/x86/hvm/emulate.c
@@ -1531,7 +1531,12 @@ static int hvmemul_read_msr(
uint64_t *val,
struct x86_emulate_ctxt *ctxt)
{
- return hvm_msr_read_intercept(reg, val);
+ int rc = hvm_msr_read_intercept(reg, val);
+
+ if ( rc == X86EMUL_EXCEPTION )
+ x86_emul_hw_exception(TRAP_gp_fault, 0, ctxt);
+
+ return rc;
}
static int hvmemul_write_msr(
@@ -1539,7 +1544,12 @@ static int hvmemul_write_msr(
uint64_t val,
struct x86_emulate_ctxt *ctxt)
{
- return hvm_msr_write_intercept(reg, val, 1);
+ int rc = hvm_msr_write_intercept(reg, val, 1);
+
+ if ( rc == X86EMUL_EXCEPTION )
+ x86_emul_hw_exception(TRAP_gp_fault, 0, ctxt);
+
+ return rc;
}
static int hvmemul_wbinvd(
diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index ac207e4..863adfc 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -509,7 +509,11 @@ void hvm_do_resume(struct vcpu *v)
if ( w->do_write.msr )
{
- hvm_msr_write_intercept(w->msr, w->value, 0);
+ int rc = hvm_msr_write_intercept(w->msr, w->value, 0);
+
+ if ( rc == X86EMUL_EXCEPTION )
+ hvm_inject_hw_exception(TRAP_gp_fault, 0);
+
w->do_write.msr = 0;
}
@@ -3896,7 +3900,6 @@ int hvm_msr_read_intercept(unsigned int msr, uint64_t
*msr_content)
return ret;
gp_fault:
- hvm_inject_hw_exception(TRAP_gp_fault, 0);
ret = X86EMUL_EXCEPTION;
*msr_content = -1ull;
goto out;
@@ -4054,7 +4057,6 @@ int hvm_msr_write_intercept(unsigned int msr, uint64_t
msr_content,
return ret;
gp_fault:
- hvm_inject_hw_exception(TRAP_gp_fault, 0);
return X86EMUL_EXCEPTION;
}
diff --git a/xen/arch/x86/hvm/svm/svm.c b/xen/arch/x86/hvm/svm/svm.c
index 1588b2f..810b0d4 100644
--- a/xen/arch/x86/hvm/svm/svm.c
+++ b/xen/arch/x86/hvm/svm/svm.c
@@ -1788,7 +1788,6 @@ static int svm_msr_read_intercept(unsigned int msr,
uint64_t *msr_content)
return X86EMUL_OKAY;
gpf:
- hvm_inject_hw_exception(TRAP_gp_fault, 0);
return X86EMUL_EXCEPTION;
}
@@ -1945,7 +1944,6 @@ static int svm_msr_write_intercept(unsigned int msr,
uint64_t msr_content)
return result;
gpf:
- hvm_inject_hw_exception(TRAP_gp_fault, 0);
return X86EMUL_EXCEPTION;
}
@@ -1976,6 +1974,8 @@ static void svm_do_msr_access(struct cpu_user_regs *regs)
if ( rc == X86EMUL_OKAY )
__update_guest_eip(regs, inst_len);
+ else if ( rc == X86EMUL_EXCEPTION )
+ hvm_inject_hw_exception(TRAP_gp_fault, 0);
}
static void svm_vmexit_do_hlt(struct vmcb_struct *vmcb,
diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
index afde634..ddfb410 100644
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -2691,7 +2691,6 @@ static int vmx_msr_read_intercept(unsigned int msr,
uint64_t *msr_content)
return X86EMUL_OKAY;
gp_fault:
- hvm_inject_hw_exception(TRAP_gp_fault, 0);
return X86EMUL_EXCEPTION;
}
@@ -2920,7 +2919,6 @@ static int vmx_msr_write_intercept(unsigned int msr,
uint64_t msr_content)
return X86EMUL_OKAY;
gp_fault:
- hvm_inject_hw_exception(TRAP_gp_fault, 0);
return X86EMUL_EXCEPTION;
}
@@ -3632,23 +3630,35 @@ void vmx_vmexit_handler(struct cpu_user_regs *regs)
break;
case EXIT_REASON_MSR_READ:
{
- uint64_t msr_content;
- if ( hvm_msr_read_intercept(regs->ecx, &msr_content) == X86EMUL_OKAY )
+ uint64_t msr_content = 0;
+
+ switch ( hvm_msr_read_intercept(regs->_ecx, &msr_content) )
{
- regs->eax = (uint32_t)msr_content;
- regs->edx = (uint32_t)(msr_content >> 32);
+ case X86EMUL_OKAY:
+ regs->rax = (uint32_t)msr_content;
+ regs->rdx = (uint32_t)(msr_content >> 32);
update_guest_eip(); /* Safe: RDMSR */
+ break;
+
+ case X86EMUL_EXCEPTION:
+ hvm_inject_hw_exception(TRAP_gp_fault, 0);
+ break;
}
break;
}
case EXIT_REASON_MSR_WRITE:
- {
- uint64_t msr_content;
- msr_content = ((uint64_t)regs->edx << 32) | (uint32_t)regs->eax;
- if ( hvm_msr_write_intercept(regs->ecx, msr_content, 1) ==
X86EMUL_OKAY )
+ switch ( hvm_msr_write_intercept(
+ regs->_ecx, (regs->rdx << 32) | regs->_eax, 1) )
+ {
+ case X86EMUL_OKAY:
update_guest_eip(); /* Safe: WRMSR */
+ break;
+
+ case X86EMUL_EXCEPTION:
+ hvm_inject_hw_exception(TRAP_gp_fault, 0);
+ break;
+ }
break;
- }
case EXIT_REASON_VMXOFF:
if ( nvmx_handle_vmxoff(regs) == X86EMUL_OKAY )
diff --git a/xen/arch/x86/hvm/vmx/vvmx.c b/xen/arch/x86/hvm/vmx/vvmx.c
index e6e9ebd..87f02ef 100644
--- a/xen/arch/x86/hvm/vmx/vvmx.c
+++ b/xen/arch/x86/hvm/vmx/vvmx.c
@@ -1000,6 +1000,7 @@ static void load_shadow_guest_state(struct vcpu *v)
struct nestedvcpu *nvcpu = &vcpu_nestedhvm(v);
u32 control;
u64 cr_gh_mask, cr_read_shadow;
+ int rc;
static const u16 vmentry_fields[] = {
VM_ENTRY_INTR_INFO,
@@ -1021,8 +1022,12 @@ static void load_shadow_guest_state(struct vcpu *v)
if ( control & VM_ENTRY_LOAD_GUEST_PAT )
hvm_set_guest_pat(v, get_vvmcs(v, GUEST_PAT));
if ( control & VM_ENTRY_LOAD_PERF_GLOBAL_CTRL )
- hvm_msr_write_intercept(MSR_CORE_PERF_GLOBAL_CTRL,
- get_vvmcs(v, GUEST_PERF_GLOBAL_CTRL), 0);
+ {
+ rc = hvm_msr_write_intercept(MSR_CORE_PERF_GLOBAL_CTRL,
+ get_vvmcs(v, GUEST_PERF_GLOBAL_CTRL), 0);
+ if ( rc == X86EMUL_EXCEPTION )
+ hvm_inject_hw_exception(TRAP_gp_fault, 0);
+ }
hvm_funcs.set_tsc_offset(v, v->arch.hvm_vcpu.cache_tsc_offset, 0);
@@ -1193,7 +1198,7 @@ static void sync_vvmcs_ro(struct vcpu *v)
static void load_vvmcs_host_state(struct vcpu *v)
{
- int i;
+ int i, rc;
u64 r;
u32 control;
@@ -1211,8 +1216,12 @@ static void load_vvmcs_host_state(struct vcpu *v)
if ( control & VM_EXIT_LOAD_HOST_PAT )
hvm_set_guest_pat(v, get_vvmcs(v, HOST_PAT));
if ( control & VM_EXIT_LOAD_PERF_GLOBAL_CTRL )
- hvm_msr_write_intercept(MSR_CORE_PERF_GLOBAL_CTRL,
- get_vvmcs(v, HOST_PERF_GLOBAL_CTRL), 1);
+ {
+ rc = hvm_msr_write_intercept(MSR_CORE_PERF_GLOBAL_CTRL,
+ get_vvmcs(v, HOST_PERF_GLOBAL_CTRL), 1);
+ if ( rc == X86EMUL_EXCEPTION )
+ hvm_inject_hw_exception(TRAP_gp_fault, 0);
+ }
hvm_funcs.set_tsc_offset(v, v->arch.hvm_vcpu.cache_tsc_offset, 0);
diff --git a/xen/include/asm-x86/hvm/support.h
b/xen/include/asm-x86/hvm/support.h
index 3d767d7..2bff1f4 100644
--- a/xen/include/asm-x86/hvm/support.h
+++ b/xen/include/asm-x86/hvm/support.h
@@ -122,13 +122,18 @@ int hvm_set_efer(uint64_t value);
int hvm_set_cr0(unsigned long value, bool_t may_defer);
int hvm_set_cr3(unsigned long value, bool_t may_defer);
int hvm_set_cr4(unsigned long value, bool_t may_defer);
-int hvm_msr_read_intercept(unsigned int msr, uint64_t *msr_content);
-int hvm_msr_write_intercept(
- unsigned int msr, uint64_t msr_content, bool_t may_defer);
int hvm_mov_to_cr(unsigned int cr, unsigned int gpr);
int hvm_mov_from_cr(unsigned int cr, unsigned int gpr);
void hvm_ud_intercept(struct cpu_user_regs *);
+/*
+ * May return X86EMUL_EXCEPTION, at which point the caller is responsible for
+ * injecting a #GP fault. Used to support speculative reads.
+ */
+int hvm_msr_read_intercept(unsigned int msr, uint64_t *msr_content);
+int hvm_msr_write_intercept(
+ unsigned int msr, uint64_t msr_content, bool_t may_defer);
+
#endif /* __ASM_X86_HVM_SUPPORT_H__ */
/*
--
2.1.4
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