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authorHou Wenlong <houwenlong.hwl@antgroup.com>2022-03-07 20:26:33 +0800
committerPaolo Bonzini <pbonzini@redhat.com>2022-04-02 05:34:47 -0400
commitac8d6cad3c7b39633d5899dc2fa9abec7135e83e (patch)
tree6945076bc75b5369bb1ab93bf56b0d891fd0c605
parenta836839cbfe60dc434c5476a7429cf2bae36415d (diff)
KVM: x86: Only do MSR filtering when access MSR by rdmsr/wrmsr
If MSR access is rejected by MSR filtering, kvm_set_msr()/kvm_get_msr() would return KVM_MSR_RET_FILTERED, and the return value is only handled well for rdmsr/wrmsr. However, some instruction emulation and state transition also use kvm_set_msr()/kvm_get_msr() to do msr access but may trigger some unexpected results if MSR access is rejected, E.g. RDPID emulation would inject a #UD but RDPID wouldn't cause a exit when RDPID is supported in hardware and ENABLE_RDTSCP is set. And it would also cause failure when load MSR at nested entry/exit. Since msr filtering is based on MSR bitmap, it is better to only do MSR filtering for rdmsr/wrmsr. Signed-off-by: Hou Wenlong <houwenlong.hwl@antgroup.com> Message-Id: <2b2774154f7532c96a6f04d71c82a8bec7d9e80b.1646655860.git.houwenlong.hwl@antgroup.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
-rw-r--r--arch/x86/kvm/emulate.c4
-rw-r--r--arch/x86/kvm/kvm_emulate.h2
-rw-r--r--arch/x86/kvm/x86.c50
3 files changed, 40 insertions, 16 deletions
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index c9f87c079d88..be83c9c8482d 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -3625,7 +3625,7 @@ static int em_wrmsr(struct x86_emulate_ctxt *ctxt)
msr_data = (u32)reg_read(ctxt, VCPU_REGS_RAX)
| ((u64)reg_read(ctxt, VCPU_REGS_RDX) << 32);
- r = ctxt->ops->set_msr(ctxt, msr_index, msr_data);
+ r = ctxt->ops->set_msr_with_filter(ctxt, msr_index, msr_data);
if (r == X86EMUL_IO_NEEDED)
return r;
@@ -3642,7 +3642,7 @@ static int em_rdmsr(struct x86_emulate_ctxt *ctxt)
u64 msr_data;
int r;
- r = ctxt->ops->get_msr(ctxt, msr_index, &msr_data);
+ r = ctxt->ops->get_msr_with_filter(ctxt, msr_index, &msr_data);
if (r == X86EMUL_IO_NEEDED)
return r;
diff --git a/arch/x86/kvm/kvm_emulate.h b/arch/x86/kvm/kvm_emulate.h
index a2a7654d8ace..1cbd46cf71f9 100644
--- a/arch/x86/kvm/kvm_emulate.h
+++ b/arch/x86/kvm/kvm_emulate.h
@@ -210,6 +210,8 @@ struct x86_emulate_ops {
int (*set_dr)(struct x86_emulate_ctxt *ctxt, int dr, ulong value);
u64 (*get_smbase)(struct x86_emulate_ctxt *ctxt);
void (*set_smbase)(struct x86_emulate_ctxt *ctxt, u64 smbase);
+ int (*set_msr_with_filter)(struct x86_emulate_ctxt *ctxt, u32 msr_index, u64 data);
+ int (*get_msr_with_filter)(struct x86_emulate_ctxt *ctxt, u32 msr_index, u64 *pdata);
int (*set_msr)(struct x86_emulate_ctxt *ctxt, u32 msr_index, u64 data);
int (*get_msr)(struct x86_emulate_ctxt *ctxt, u32 msr_index, u64 *pdata);
int (*check_pmc)(struct x86_emulate_ctxt *ctxt, u32 pmc);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 2c131125774d..bc63ba52c4d6 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1748,9 +1748,6 @@ static int __kvm_set_msr(struct kvm_vcpu *vcpu, u32 index, u64 data,
{
struct msr_data msr;
- if (!host_initiated && !kvm_msr_allowed(vcpu, index, KVM_MSR_FILTER_WRITE))
- return KVM_MSR_RET_FILTERED;
-
switch (index) {
case MSR_FS_BASE:
case MSR_GS_BASE:
@@ -1832,9 +1829,6 @@ int __kvm_get_msr(struct kvm_vcpu *vcpu, u32 index, u64 *data,
struct msr_data msr;
int ret;
- if (!host_initiated && !kvm_msr_allowed(vcpu, index, KVM_MSR_FILTER_READ))
- return KVM_MSR_RET_FILTERED;
-
switch (index) {
case MSR_TSC_AUX:
if (!kvm_is_supported_user_return_msr(MSR_TSC_AUX))
@@ -1871,6 +1865,20 @@ static int kvm_get_msr_ignored_check(struct kvm_vcpu *vcpu,
return ret;
}
+static int kvm_get_msr_with_filter(struct kvm_vcpu *vcpu, u32 index, u64 *data)
+{
+ if (!kvm_msr_allowed(vcpu, index, KVM_MSR_FILTER_READ))
+ return KVM_MSR_RET_FILTERED;
+ return kvm_get_msr_ignored_check(vcpu, index, data, false);
+}
+
+static int kvm_set_msr_with_filter(struct kvm_vcpu *vcpu, u32 index, u64 data)
+{
+ if (!kvm_msr_allowed(vcpu, index, KVM_MSR_FILTER_WRITE))
+ return KVM_MSR_RET_FILTERED;
+ return kvm_set_msr_ignored_check(vcpu, index, data, false);
+}
+
int kvm_get_msr(struct kvm_vcpu *vcpu, u32 index, u64 *data)
{
return kvm_get_msr_ignored_check(vcpu, index, data, false);
@@ -1953,7 +1961,7 @@ int kvm_emulate_rdmsr(struct kvm_vcpu *vcpu)
u64 data;
int r;
- r = kvm_get_msr(vcpu, ecx, &data);
+ r = kvm_get_msr_with_filter(vcpu, ecx, &data);
if (!r) {
trace_kvm_msr_read(ecx, data);
@@ -1978,7 +1986,7 @@ int kvm_emulate_wrmsr(struct kvm_vcpu *vcpu)
u64 data = kvm_read_edx_eax(vcpu);
int r;
- r = kvm_set_msr(vcpu, ecx, data);
+ r = kvm_set_msr_with_filter(vcpu, ecx, data);
if (!r) {
trace_kvm_msr_write(ecx, data);
@@ -7631,13 +7639,13 @@ static void emulator_set_segment(struct x86_emulate_ctxt *ctxt, u16 selector,
return;
}
-static int emulator_get_msr(struct x86_emulate_ctxt *ctxt,
- u32 msr_index, u64 *pdata)
+static int emulator_get_msr_with_filter(struct x86_emulate_ctxt *ctxt,
+ u32 msr_index, u64 *pdata)
{
struct kvm_vcpu *vcpu = emul_to_vcpu(ctxt);
int r;
- r = kvm_get_msr(vcpu, msr_index, pdata);
+ r = kvm_get_msr_with_filter(vcpu, msr_index, pdata);
if (r && kvm_msr_user_space(vcpu, msr_index, KVM_EXIT_X86_RDMSR, 0,
complete_emulated_rdmsr, r)) {
@@ -7648,13 +7656,13 @@ static int emulator_get_msr(struct x86_emulate_ctxt *ctxt,
return r;
}
-static int emulator_set_msr(struct x86_emulate_ctxt *ctxt,
- u32 msr_index, u64 data)
+static int emulator_set_msr_with_filter(struct x86_emulate_ctxt *ctxt,
+ u32 msr_index, u64 data)
{
struct kvm_vcpu *vcpu = emul_to_vcpu(ctxt);
int r;
- r = kvm_set_msr(vcpu, msr_index, data);
+ r = kvm_set_msr_with_filter(vcpu, msr_index, data);
if (r && kvm_msr_user_space(vcpu, msr_index, KVM_EXIT_X86_WRMSR, data,
complete_emulated_msr_access, r)) {
@@ -7665,6 +7673,18 @@ static int emulator_set_msr(struct x86_emulate_ctxt *ctxt,
return r;
}
+static int emulator_get_msr(struct x86_emulate_ctxt *ctxt,
+ u32 msr_index, u64 *pdata)
+{
+ return kvm_get_msr(emul_to_vcpu(ctxt), msr_index, pdata);
+}
+
+static int emulator_set_msr(struct x86_emulate_ctxt *ctxt,
+ u32 msr_index, u64 data)
+{
+ return kvm_set_msr(emul_to_vcpu(ctxt), msr_index, data);
+}
+
static u64 emulator_get_smbase(struct x86_emulate_ctxt *ctxt)
{
struct kvm_vcpu *vcpu = emul_to_vcpu(ctxt);
@@ -7803,6 +7823,8 @@ static const struct x86_emulate_ops emulate_ops = {
.set_dr = emulator_set_dr,
.get_smbase = emulator_get_smbase,
.set_smbase = emulator_set_smbase,
+ .set_msr_with_filter = emulator_set_msr_with_filter,
+ .get_msr_with_filter = emulator_get_msr_with_filter,
.set_msr = emulator_set_msr,
.get_msr = emulator_get_msr,
.check_pmc = emulator_check_pmc,