[PATCH RESEND 28/30] KVM: SVM: implement force_intercept_exceptions_mask
From: Maxim Levitsky
Date: Mon Feb 07 2022 - 11:16:52 EST
Currently #TS interception is only done once.
Also exception interception is not enabled for SEV guests.
Signed-off-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx>
---
arch/x86/include/asm/kvm_host.h | 2 +
arch/x86/include/uapi/asm/kvm.h | 1 +
arch/x86/kvm/svm/svm.c | 92 ++++++++++++++++++++++++++++++++-
arch/x86/kvm/svm/svm.h | 5 +-
arch/x86/kvm/svm/svm_onhyperv.c | 1 +
arch/x86/kvm/x86.c | 5 +-
6 files changed, 101 insertions(+), 5 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index fa498612839a0..446ee29e6cc99 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1750,6 +1750,8 @@ int kvm_emulate_rdpmc(struct kvm_vcpu *vcpu);
void kvm_queue_exception(struct kvm_vcpu *vcpu, unsigned nr);
void kvm_queue_exception_e(struct kvm_vcpu *vcpu, unsigned nr, u32 error_code);
void kvm_queue_exception_p(struct kvm_vcpu *vcpu, unsigned nr, unsigned long payload);
+void kvm_queue_exception_e_p(struct kvm_vcpu *vcpu, unsigned nr,
+ u32 error_code, unsigned long payload);
void kvm_requeue_exception(struct kvm_vcpu *vcpu, unsigned nr);
void kvm_requeue_exception_e(struct kvm_vcpu *vcpu, unsigned nr, u32 error_code);
void kvm_inject_page_fault(struct kvm_vcpu *vcpu, struct x86_exception *fault);
diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h
index bf6e96011dfed..d462b4808e893 100644
--- a/arch/x86/include/uapi/asm/kvm.h
+++ b/arch/x86/include/uapi/asm/kvm.h
@@ -32,6 +32,7 @@
#define MC_VECTOR 18
#define XM_VECTOR 19
#define VE_VECTOR 20
+#define CP_VECTOR 21
/* Select x86 specific features in <linux/kvm.h> */
#define __KVM_HAVE_PIT
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 1cf682d1553cc..afa4116ea938c 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -245,6 +245,8 @@ static const u32 msrpm_ranges[] = {0, 0xc0000000, 0xc0010000};
#define MSRS_RANGE_SIZE 2048
#define MSRS_IN_RANGE (MSRS_RANGE_SIZE * 8 / 2)
+static int svm_handle_invalid_exit(struct kvm_vcpu *vcpu, u64 exit_code);
+
u32 svm_msrpm_offset(u32 msr)
{
u32 offset;
@@ -1035,6 +1037,16 @@ static void svm_recalc_instruction_intercepts(struct kvm_vcpu *vcpu,
}
}
+static void svm_init_force_exceptions_intercepts(struct kvm_vcpu *vcpu)
+{
+ int exc;
+ struct vcpu_svm *svm = to_svm(vcpu);
+
+ for (exc = 0 ; exc < 32 ; ++exc)
+ if (kvm_is_exception_force_intercepted(vcpu->kvm, exc))
+ set_exception_intercept(svm, exc);
+}
+
static inline void init_vmcb_after_set_cpuid(struct kvm_vcpu *vcpu)
{
struct vcpu_svm *svm = to_svm(vcpu);
@@ -1235,6 +1247,8 @@ static void __svm_vcpu_reset(struct kvm_vcpu *vcpu)
if (sev_es_guest(vcpu->kvm))
sev_es_vcpu_reset(svm);
+ else
+ svm_init_force_exceptions_intercepts(vcpu);
}
static void svm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
@@ -1865,6 +1879,19 @@ static int pf_interception(struct kvm_vcpu *vcpu)
u64 fault_address = svm->vmcb->control.exit_info_2;
u64 error_code = svm->vmcb->control.exit_info_1;
+
+ if (kvm_is_exception_force_intercepted(vcpu->kvm, PF_VECTOR)) {
+ if (npt_enabled && !vcpu->arch.apf.host_apf_flags) {
+ /* If the #PF was only intercepted for debug, inject
+ * it directly to the guest, since the kvm's mmu code
+ * is not ready to deal with such page faults.
+ */
+ kvm_queue_exception_e_p(vcpu, PF_VECTOR,
+ error_code, fault_address);
+ return 1;
+ }
+ }
+
return kvm_handle_page_fault(vcpu, error_code, fault_address,
static_cpu_has(X86_FEATURE_DECODEASSISTS) ?
svm->vmcb->control.insn_bytes : NULL,
@@ -1940,6 +1967,46 @@ static int ac_interception(struct kvm_vcpu *vcpu)
return 1;
}
+static int gen_exc_interception(struct kvm_vcpu *vcpu)
+{
+ /*
+ * Generic exception intercept handler which forwards a guest exception
+ * as-is to the guest.
+ * For exceptions that don't have a special intercept handler.
+ *
+ * Used only for 'force_intercept_exceptions_mask' KVM debug feature.
+ */
+ struct vcpu_svm *svm = to_svm(vcpu);
+ int exc = svm->vmcb->control.exit_code - SVM_EXIT_EXCP_BASE;
+
+ if (!kvm_is_exception_force_intercepted(vcpu->kvm, exc))
+ return svm_handle_invalid_exit(vcpu, svm->vmcb->control.exit_code);
+
+ if (x86_exception_has_error_code(exc)) {
+
+ if (exc == TS_VECTOR) {
+ /*
+ * SVM doesn't provide us with an error code to be able to
+ * re-inject the #TS exception, so just disable its
+ * intercept, and let the guest re-execute the instruction.
+ */
+ vmcb_clr_intercept(&svm->vmcb01.ptr->control,
+ INTERCEPT_EXCEPTION_OFFSET + TS_VECTOR);
+ recalc_intercepts(svm);
+ return 1;
+ } else if (exc == DF_VECTOR) {
+ /*
+ * SVM doesn't provide the error code on #DF either
+ * but it is always 0
+ */
+ svm->vmcb->control.exit_info_1 = 0;
+ }
+ kvm_queue_exception_e(vcpu, exc, svm->vmcb->control.exit_info_1);
+ } else
+ kvm_queue_exception(vcpu, exc);
+ return 1;
+}
+
static bool is_erratum_383(void)
{
int err, i;
@@ -3050,13 +3117,34 @@ static int (*const svm_exit_handlers[])(struct kvm_vcpu *vcpu) = {
[SVM_EXIT_WRITE_DR5] = dr_interception,
[SVM_EXIT_WRITE_DR6] = dr_interception,
[SVM_EXIT_WRITE_DR7] = dr_interception,
+
+ /* 0 */
+ [SVM_EXIT_EXCP_BASE + DE_VECTOR] = gen_exc_interception,
[SVM_EXIT_EXCP_BASE + DB_VECTOR] = db_interception,
+ /* NMI*/
[SVM_EXIT_EXCP_BASE + BP_VECTOR] = bp_interception,
+ [SVM_EXIT_EXCP_BASE + OF_VECTOR] = gen_exc_interception,
+ [SVM_EXIT_EXCP_BASE + BR_VECTOR] = gen_exc_interception,
[SVM_EXIT_EXCP_BASE + UD_VECTOR] = ud_interception,
+ [SVM_EXIT_EXCP_BASE + NM_VECTOR] = gen_exc_interception,
+ /* 8*/
+ [SVM_EXIT_EXCP_BASE + DF_VECTOR] = gen_exc_interception,
+ /* 9 is reserved*/
+ [SVM_EXIT_EXCP_BASE + TS_VECTOR] = gen_exc_interception,
+ [SVM_EXIT_EXCP_BASE + NP_VECTOR] = gen_exc_interception,
+ [SVM_EXIT_EXCP_BASE + SS_VECTOR] = gen_exc_interception,
+ [SVM_EXIT_EXCP_BASE + GP_VECTOR] = gp_interception,
[SVM_EXIT_EXCP_BASE + PF_VECTOR] = pf_interception,
- [SVM_EXIT_EXCP_BASE + MC_VECTOR] = mc_interception,
+ /* 15 is reserved*/
+ /* 16 */
+ [SVM_EXIT_EXCP_BASE + MF_VECTOR] = gen_exc_interception,
[SVM_EXIT_EXCP_BASE + AC_VECTOR] = ac_interception,
- [SVM_EXIT_EXCP_BASE + GP_VECTOR] = gp_interception,
+ [SVM_EXIT_EXCP_BASE + MC_VECTOR] = mc_interception,
+ [SVM_EXIT_EXCP_BASE + XM_VECTOR] = gen_exc_interception,
+ /* 20 - #VE - reserved on AMD*/
+ [SVM_EXIT_EXCP_BASE + CP_VECTOR] = gen_exc_interception,
+ /* TODO: exceptions 22-31 */
+
[SVM_EXIT_INTR] = intr_interception,
[SVM_EXIT_NMI] = nmi_interception,
[SVM_EXIT_SMI] = smi_interception,
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index 73cc9d3e784bd..dd3671d77258b 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -415,8 +415,11 @@ static inline void clr_exception_intercept(struct vcpu_svm *svm, u32 bit)
struct vmcb *vmcb = svm->vmcb01.ptr;
WARN_ON_ONCE(bit >= 32);
- vmcb_clr_intercept(&vmcb->control, INTERCEPT_EXCEPTION_OFFSET + bit);
+ if (kvm_is_exception_force_intercepted(svm->vcpu.kvm, bit))
+ return;
+
+ vmcb_clr_intercept(&vmcb->control, INTERCEPT_EXCEPTION_OFFSET + bit);
recalc_intercepts(svm);
}
diff --git a/arch/x86/kvm/svm/svm_onhyperv.c b/arch/x86/kvm/svm/svm_onhyperv.c
index 98aa981c04ec5..81be254e757b2 100644
--- a/arch/x86/kvm/svm/svm_onhyperv.c
+++ b/arch/x86/kvm/svm/svm_onhyperv.c
@@ -8,6 +8,7 @@
#include <asm/mshyperv.h>
+#include "x86.h"
#include "svm.h"
#include "svm_ops.h"
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 202c34697852f..0ee2fbb068b17 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -706,12 +706,13 @@ void kvm_queue_exception_p(struct kvm_vcpu *vcpu, unsigned nr,
}
EXPORT_SYMBOL_GPL(kvm_queue_exception_p);
-static void kvm_queue_exception_e_p(struct kvm_vcpu *vcpu, unsigned nr,
- u32 error_code, unsigned long payload)
+void kvm_queue_exception_e_p(struct kvm_vcpu *vcpu, unsigned nr,
+ u32 error_code, unsigned long payload)
{
kvm_multiple_exception(vcpu, nr, true, error_code,
true, payload, false);
}
+EXPORT_SYMBOL_GPL(kvm_queue_exception_e_p);
int kvm_complete_insn_gp(struct kvm_vcpu *vcpu, int err)
{
--
2.26.3