[PATCH v4 17/23] KVM: x86: smm: use smram structs in the common code

From: Maxim Levitsky
Date: Tue Oct 25 2022 - 08:46:34 EST


Use kvm_smram union instad of raw arrays in the common smm code.

Signed-off-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx>
---
arch/x86/include/asm/kvm_host.h | 5 +++--
arch/x86/kvm/smm.c | 27 ++++++++++++++-------------
arch/x86/kvm/svm/svm.c | 8 ++++++--
arch/x86/kvm/vmx/vmx.c | 4 ++--
4 files changed, 25 insertions(+), 19 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 0b0a82c0bb5cbd..540ff3122bbf8e 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -206,6 +206,7 @@ typedef enum exit_fastpath_completion fastpath_t;

struct x86_emulate_ctxt;
struct x86_exception;
+union kvm_smram;
enum x86_intercept;
enum x86_intercept_stage;

@@ -1611,8 +1612,8 @@ struct kvm_x86_ops {

#ifdef CONFIG_KVM_SMM
int (*smi_allowed)(struct kvm_vcpu *vcpu, bool for_injection);
- int (*enter_smm)(struct kvm_vcpu *vcpu, char *smstate);
- int (*leave_smm)(struct kvm_vcpu *vcpu, const char *smstate);
+ int (*enter_smm)(struct kvm_vcpu *vcpu, union kvm_smram *smram);
+ int (*leave_smm)(struct kvm_vcpu *vcpu, const union kvm_smram *smram);
void (*enable_smi_window)(struct kvm_vcpu *vcpu);
#endif

diff --git a/arch/x86/kvm/smm.c b/arch/x86/kvm/smm.c
index 01dab9fc3ab4b7..e714d43b746cce 100644
--- a/arch/x86/kvm/smm.c
+++ b/arch/x86/kvm/smm.c
@@ -288,17 +288,18 @@ void enter_smm(struct kvm_vcpu *vcpu)
struct kvm_segment cs, ds;
struct desc_ptr dt;
unsigned long cr0;
- char buf[512];
+ union kvm_smram smram;

check_smram_offsets();

- memset(buf, 0, 512);
+ memset(smram.bytes, 0, sizeof(smram.bytes));
+
#ifdef CONFIG_X86_64
if (guest_cpuid_has(vcpu, X86_FEATURE_LM))
- enter_smm_save_state_64(vcpu, buf);
+ enter_smm_save_state_64(vcpu, smram.bytes);
else
#endif
- enter_smm_save_state_32(vcpu, buf);
+ enter_smm_save_state_32(vcpu, smram.bytes);

/*
* Give enter_smm() a chance to make ISA-specific changes to the vCPU
@@ -308,12 +309,12 @@ void enter_smm(struct kvm_vcpu *vcpu)
* Kill the VM in the unlikely case of failure, because the VM
* can be in undefined state in this case.
*/
- if (static_call(kvm_x86_enter_smm)(vcpu, buf))
+ if (static_call(kvm_x86_enter_smm)(vcpu, &smram))
goto error;

kvm_smm_changed(vcpu, true);

- if (kvm_vcpu_write_guest(vcpu, vcpu->arch.smbase + 0xfe00, buf, sizeof(buf)))
+ if (kvm_vcpu_write_guest(vcpu, vcpu->arch.smbase + 0xfe00, &smram, sizeof(smram)))
goto error;

if (static_call(kvm_x86_get_nmi_mask)(vcpu))
@@ -473,7 +474,7 @@ static int rsm_enter_protected_mode(struct kvm_vcpu *vcpu,
}

static int rsm_load_state_32(struct x86_emulate_ctxt *ctxt,
- const char *smstate)
+ u8 *smstate)
{
struct kvm_vcpu *vcpu = ctxt->vcpu;
struct kvm_segment desc;
@@ -534,7 +535,7 @@ static int rsm_load_state_32(struct x86_emulate_ctxt *ctxt,

#ifdef CONFIG_X86_64
static int rsm_load_state_64(struct x86_emulate_ctxt *ctxt,
- const char *smstate)
+ u8 *smstate)
{
struct kvm_vcpu *vcpu = ctxt->vcpu;
struct kvm_segment desc;
@@ -606,13 +607,13 @@ int emulator_leave_smm(struct x86_emulate_ctxt *ctxt)
{
struct kvm_vcpu *vcpu = ctxt->vcpu;
unsigned long cr0, cr4, efer;
- char buf[512];
+ union kvm_smram smram;
u64 smbase;
int ret;

smbase = vcpu->arch.smbase;

- ret = kvm_vcpu_read_guest(vcpu, smbase + 0xfe00, buf, sizeof(buf));
+ ret = kvm_vcpu_read_guest(vcpu, smbase + 0xfe00, smram.bytes, sizeof(smram));
if (ret < 0)
return X86EMUL_UNHANDLEABLE;

@@ -666,13 +667,13 @@ int emulator_leave_smm(struct x86_emulate_ctxt *ctxt)
* state (e.g. enter guest mode) before loading state from the SMM
* state-save area.
*/
- if (static_call(kvm_x86_leave_smm)(vcpu, buf))
+ if (static_call(kvm_x86_leave_smm)(vcpu, &smram))
return X86EMUL_UNHANDLEABLE;

#ifdef CONFIG_X86_64
if (guest_cpuid_has(vcpu, X86_FEATURE_LM))
- return rsm_load_state_64(ctxt, buf);
+ return rsm_load_state_64(ctxt, smram.bytes);
else
#endif
- return rsm_load_state_32(ctxt, buf);
+ return rsm_load_state_32(ctxt, smram.bytes);
}
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 2200b8aa727398..4cbb95796dcd63 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -4436,12 +4436,14 @@ static int svm_smi_allowed(struct kvm_vcpu *vcpu, bool for_injection)
return 1;
}

-static int svm_enter_smm(struct kvm_vcpu *vcpu, char *smstate)
+static int svm_enter_smm(struct kvm_vcpu *vcpu, union kvm_smram *smram)
{
struct vcpu_svm *svm = to_svm(vcpu);
struct kvm_host_map map_save;
int ret;

+ char *smstate = (char *)smram;
+
if (!is_guest_mode(vcpu))
return 0;

@@ -4483,7 +4485,7 @@ static int svm_enter_smm(struct kvm_vcpu *vcpu, char *smstate)
return 0;
}

-static int svm_leave_smm(struct kvm_vcpu *vcpu, const char *smstate)
+static int svm_leave_smm(struct kvm_vcpu *vcpu, const union kvm_smram *smram)
{
struct vcpu_svm *svm = to_svm(vcpu);
struct kvm_host_map map, map_save;
@@ -4491,6 +4493,8 @@ static int svm_leave_smm(struct kvm_vcpu *vcpu, const char *smstate)
struct vmcb *vmcb12;
int ret;

+ const char *smstate = (const char *)smram;
+
if (!guest_cpuid_has(vcpu, X86_FEATURE_LM))
return 0;

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 107fc035c91b80..8c7890af11fb21 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -7914,7 +7914,7 @@ static int vmx_smi_allowed(struct kvm_vcpu *vcpu, bool for_injection)
return !is_smm(vcpu);
}

-static int vmx_enter_smm(struct kvm_vcpu *vcpu, char *smstate)
+static int vmx_enter_smm(struct kvm_vcpu *vcpu, union kvm_smram *smram)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);

@@ -7935,7 +7935,7 @@ static int vmx_enter_smm(struct kvm_vcpu *vcpu, char *smstate)
return 0;
}

-static int vmx_leave_smm(struct kvm_vcpu *vcpu, const char *smstate)
+static int vmx_leave_smm(struct kvm_vcpu *vcpu, const union kvm_smram *smram)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
int ret;
--
2.34.3