[PATCH 7/9] Add VMRUN handler v2

Alexander Graf
2008-09-05T07:51:28Z

This patch implements VMRUN. VMRUN enters a virtual CPU and runs that
in the same context as the normal guest CPU would run.
So basically it is implemented the same way, a normal CPU would do it.

We also prepare all intercepts that get OR'ed with the original
intercepts, as we do not allow a level 2 guest to be intercepted less
than the first level guest.

v2 implements the following improvements:

- fixes the CPL check
- does not allocate iopm when not used
- remembers the host's IF in the HIF bit in the hflags

Signed-off-by: Alexander Graf <agraf@suse.de>
---
arch/x86/kvm/kvm_svm.h | 9 ++
arch/x86/kvm/svm.c | 198 +++++++++++++++++++++++++++++++++++++++++++-
include/asm-x86/kvm_host.h | 1 +
3 files changed, 206 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/kvm_svm.h b/arch/x86/kvm/kvm_svm.h
index 76ad107..2afe0ce 100644
--- a/arch/x86/kvm/kvm_svm.h
+++ b/arch/x86/kvm/kvm_svm.h
@@ -43,6 +43,15 @@ struct vcpu_svm {
u32 *msrpm;

u64 nested_hsave;
+ u64 nested_vmcb;
+
+ /* These are the merged vectors */
+ u32 *nested_msrpm;
+ u32 *nested_iopm;
+
+ /* gpa pointers to the real vectors */
+ u64 nested_vmcb_msrpm;
+ u64 nested_vmcb_iopm;
};

#endif
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 43ca2d8..c47f039 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -51,6 +51,9 @@ MODULE_LICENSE("GPL");
/* Turn on to get debugging output*/
/* #define NESTED_DEBUG */

+/* Not needed until device passthrough */
+/* #define NESTED_KVM_MERGE_IOPM */
+
#ifdef NESTED_DEBUG
#define nsvm_printk(fmt, args...) printk(KERN_INFO fmt, ## args)
#else
@@ -76,6 +79,11 @@ static inline struct vcpu_svm *to_svm(struct kvm_vcpu *vcpu)
return container_of(vcpu, struct vcpu_svm, vcpu);
}

+static inline bool is_nested(struct vcpu_svm *svm)
+{
+ return svm->nested_vmcb;
+}
+
static unsigned long iopm_base;

struct kvm_ldttss_desc {
@@ -614,6 +622,7 @@ static void init_vmcb(struct vcpu_svm *svm)
force_new_asid(&svm->vcpu);

svm->nested_hsave = 0;
+ svm->nested_vmcb = 0;
svm->vcpu.arch.hflags = HF_GIF_MASK;
}

@@ -639,6 +648,10 @@ static struct kvm_vcpu *svm_create_vcpu(struct kvm *kvm, unsigned int id)
struct vcpu_svm *svm;
struct page *page;
struct page *msrpm_pages;
+ struct page *nested_msrpm_pages;
+#ifdef NESTED_KVM_MERGE_IOPM
+ struct page *nested_iopm_pages;
+#endif
int err;

svm = kmem_cache_zalloc(kvm_vcpu_cache, GFP_KERNEL);
@@ -661,9 +674,25 @@ static struct kvm_vcpu *svm_create_vcpu(struct kvm *kvm, unsigned int id)
msrpm_pages = alloc_pages(GFP_KERNEL, MSRPM_ALLOC_ORDER);
if (!msrpm_pages)
goto uninit;
+
+ nested_msrpm_pages = alloc_pages(GFP_KERNEL, MSRPM_ALLOC_ORDER);
+ if (!nested_msrpm_pages)
+ goto uninit;
+
+#ifdef NESTED_KVM_MERGE_IOPM
+ nested_iopm_pages = alloc_pages(GFP_KERNEL, IOPM_ALLOC_ORDER);
+ if (!nested_iopm_pages)
+ goto uninit;
+#endif
+
svm->msrpm = page_address(msrpm_pages);
svm_vcpu_init_msrpm(svm->msrpm);

+ svm->nested_msrpm = page_address(nested_msrpm_pages);
+#ifdef NESTED_KVM_MERGE_IOPM
+ svm->nested_iopm = page_address(nested_iopm_pages);
+#endif
+
svm->vmcb = page_address(page);
clear_page(svm->vmcb);
svm->vmcb_pa = page_to_pfn(page) << PAGE_SHIFT;
@@ -693,6 +722,10 @@ static void svm_free_vcpu(struct kvm_vcpu *vcpu)

__free_page(pfn_to_page(svm->vmcb_pa >> PAGE_SHIFT));
__free_pages(virt_to_page(svm->msrpm), MSRPM_ALLOC_ORDER);
+ __free_pages(virt_to_page(svm->nested_msrpm), MSRPM_ALLOC_ORDER);
+#ifdef NESTED_KVM_MERGE_IOPM
+ __free_pages(virt_to_page(svm->nested_iopm), IOPM_ALLOC_ORDER);
+#endif
kvm_vcpu_uninit(vcpu);
kmem_cache_free(kvm_vcpu_cache, svm);
}
@@ -1218,6 +1251,133 @@ static int nested_svm_do(struct vcpu_svm *svm,
return retval;
}

+
+static int nested_svm_vmrun_msrpm(struct vcpu_svm *svm, void *arg1,
+ void *arg2, void *opaque)
+{
+ int i;
+ u32 *nested_msrpm = (u32*)arg1;
+ for (i=0; i< PAGE_SIZE * (1 << MSRPM_ALLOC_ORDER) / 4; i++)
+ svm->nested_msrpm[i] = svm->msrpm[i] | nested_msrpm[i];
+ svm->vmcb->control.msrpm_base_pa = __pa(svm->nested_msrpm);
+
+ return 0;
+}
+
+#ifdef NESTED_KVM_MERGE_IOPM
+static int nested_svm_vmrun_iopm(struct vcpu_svm *svm, void *arg1,
+ void *arg2, void *opaque)
+{
+ int i;
+ u32 *nested_iopm = (u32*)arg1;
+ u32 *iopm = (u32*)__va(iopm_base);
+ for (i=0; i< PAGE_SIZE * (1 << IOPM_ALLOC_ORDER) / 4; i++)
+ svm->nested_iopm[i] = iopm[i] | nested_iopm[i];
+ svm->vmcb->control.iopm_base_pa = __pa(svm->nested_iopm);
+
+ return 0;
+}
+#endif
+
+static int nested_svm_vmrun(struct vcpu_svm *svm, void *arg1,
+ void *arg2, void *opaque)
+{
+ struct vmcb *nested_vmcb = (struct vmcb *)arg1;
+ struct vmcb *hsave = (struct vmcb *)arg2;
+
+ /* nested_vmcb is our indicator if nested SVM is activated */
+ svm->nested_vmcb = svm->vmcb->save.rax;
+
+ /* Clear internal status */
+ svm->vcpu.arch.exception.pending = false;
+
+ /* Save the old vmcb, so we don't need to pick what we save, but
+ can restore everything when a VMEXIT occurs */
+ memcpy(hsave, svm->vmcb, sizeof(struct vmcb));
+ /* We need to remember the original CR3 in the SPT case */
+ if (!npt_enabled)
+ hsave->save.cr3 = svm->vcpu.arch.cr3;
+ hsave->save.rip = svm->next_rip;
+
+ if (svm->vmcb->save.rflags & X86_EFLAGS_IF)
+ svm->vcpu.arch.hflags |= HF_HIF_MASK;
+ else
+ svm->vcpu.arch.hflags &= ~HF_HIF_MASK;
+
+ /* Load the nested guest state */
+ svm->vmcb->save.es = nested_vmcb->save.es;
+ svm->vmcb->save.cs = nested_vmcb->save.cs;
+ svm->vmcb->save.ss = nested_vmcb->save.ss;
+ svm->vmcb->save.ds = nested_vmcb->save.ds;
+ svm->vmcb->save.gdtr = nested_vmcb->save.gdtr;
+ svm->vmcb->save.idtr = nested_vmcb->save.idtr;
+ svm->vmcb->save.rflags = nested_vmcb->save.rflags;
+ svm_set_efer(&svm->vcpu, nested_vmcb->save.efer);
+ svm_set_cr0(&svm->vcpu, nested_vmcb->save.cr0);
+ svm_set_cr4(&svm->vcpu, nested_vmcb->save.cr4);
+ if (npt_enabled) {
+ svm->vmcb->save.cr3 = nested_vmcb->save.cr3;
+ svm->vcpu.arch.cr3 = nested_vmcb->save.cr3;
+ } else {
+ kvm_set_cr3(&svm->vcpu, nested_vmcb->save.cr3);
+ kvm_mmu_reset_context(&svm->vcpu);
+ }
+ svm->vmcb->save.cr2 = nested_vmcb->save.cr2;
+ kvm_register_write(&svm->vcpu, VCPU_REGS_RAX, nested_vmcb->save.rax);
+ kvm_register_write(&svm->vcpu, VCPU_REGS_RSP, nested_vmcb->save.rsp);
+ kvm_register_write(&svm->vcpu, VCPU_REGS_RIP, nested_vmcb->save.rip);
+ /* In case we don't even reach vcpu_run, the fields are not updated */
+ svm->vmcb->save.rax = nested_vmcb->save.rax;
+ svm->vmcb->save.rsp = nested_vmcb->save.rsp;
+ svm->vmcb->save.rip = nested_vmcb->save.rip;
+ svm->vmcb->save.dr7 = nested_vmcb->save.dr7;
+ svm->vmcb->save.dr6 = nested_vmcb->save.dr6;
+ svm->vmcb->save.cpl = nested_vmcb->save.cpl;
+
+ /* We don't want a nested guest to be more powerful than the guest,
+ so all intercepts are ORed */
+ svm->vmcb->control.intercept_cr_read |=
+ nested_vmcb->control.intercept_cr_read;
+ svm->vmcb->control.intercept_cr_write |=
+ nested_vmcb->control.intercept_cr_write;
+ svm->vmcb->control.intercept_dr_read |=
+ nested_vmcb->control.intercept_dr_read;
+ svm->vmcb->control.intercept_dr_write |=
+ nested_vmcb->control.intercept_dr_write;
+ svm->vmcb->control.intercept_exceptions |=
+ nested_vmcb->control.intercept_exceptions;
+
+ svm->vmcb->control.intercept |= nested_vmcb->control.intercept;
+
+ svm->nested_vmcb_msrpm = nested_vmcb->control.msrpm_base_pa;
+ svm->nested_vmcb_iopm = nested_vmcb->control.iopm_base_pa;
+
+ force_new_asid(&svm->vcpu);
+ svm->vmcb->control.exit_int_info = nested_vmcb->control.exit_int_info;
+ svm->vmcb->control.exit_int_info_err = nested_vmcb->control.exit_int_info_err;
+ svm->vmcb->control.int_ctl = nested_vmcb->control.int_ctl | V_INTR_MASKING_MASK;
+ if (nested_vmcb->control.int_ctl & V_IRQ_MASK) {
+ nsvm_printk("nSVM Injecting Interrupt: 0x%x\n",
+ nested_vmcb->control.int_ctl);
+ }
+ nsvm_printk("nSVM exit_int_info: 0x%x | int_state: 0x%x\n",
+ nested_vmcb->control.exit_int_info,
+ nested_vmcb->control.int_state);
+
+ svm->vmcb->control.int_vector = nested_vmcb->control.int_vector;
+ svm->vmcb->control.int_state = nested_vmcb->control.int_state;
+ svm->vmcb->control.tsc_offset += nested_vmcb->control.tsc_offset;
+ if (nested_vmcb->control.event_inj & SVM_EVTINJ_VALID)
+ nsvm_printk("Injecting Event: 0x%x\n",
+ nested_vmcb->control.event_inj);
+ svm->vmcb->control.event_inj = nested_vmcb->control.event_inj;
+ svm->vmcb->control.event_inj_err = nested_vmcb->control.event_inj_err;
+
+ svm->vcpu.arch.hflags |= HF_GIF_MASK;
+
+ return 1;
+}
+
static int nested_svm_vmloadsave(struct vmcb *from_vmcb, struct vmcb *to_vmcb)
{
to_vmcb->save.fs = from_vmcb->save.fs;
@@ -1283,6 +1443,39 @@ static int vmsave_interception(struct vcpu_svm *svm, struct kvm_run *kvm_run)
return 1;
}

+static int vmrun_interception(struct vcpu_svm *svm, struct kvm_run *kvm_run)
+{
+ nsvm_printk("VMrun\n");
+
+ if (svm->vmcb->save.cpl) {
+ printk(KERN_ERR "%s: invalid cpl 0x%x at ip 0x%lx\n",
+ __func__, svm->vmcb->save.cpl, kvm_rip_read(&svm->vcpu));
+ kvm_queue_exception(&svm->vcpu, GP_VECTOR);
+ return 1;
+ }
+
+ svm->next_rip = kvm_rip_read(&svm->vcpu) + 3;
+ skip_emulated_instruction(&svm->vcpu);
+
+ if (nested_svm_do(svm, svm->vmcb->save.rax, svm->nested_hsave,
+ NULL, nested_svm_vmrun))
+ return 1;
+
+ /* Right now SVM always intecepts all IOs except for the DEBUG port.
+ This is fine for the nested VM too IMHO. */
+#ifdef NESTED_KVM_MERGE_IOPM
+ if (nested_svm_do(svm, svm->vmcb->control.iopm_base_pa, 0,
+ NULL, nested_svm_vmrun_iopm))
+ return 1;
+#endif
+
+ if (nested_svm_do(svm, svm->vmcb->control.msrpm_base_pa, 0,
+ NULL, nested_svm_vmrun_msrpm))
+ return 1;
+
+ return 1;
+}
+
static int stgi_interception(struct vcpu_svm *svm, struct kvm_run *kvm_run)
{
if (svm->vmcb->save.cpl) {
@@ -1617,7 +1810,7 @@ static int (*svm_exit_handlers[])(struct vcpu_svm *svm,
[SVM_EXIT_MSR] = msr_interception,
[SVM_EXIT_TASK_SWITCH] = task_switch_interception,
[SVM_EXIT_SHUTDOWN] = shutdown_interception,
- [SVM_EXIT_VMRUN] = invalid_op_interception,
+ [SVM_EXIT_VMRUN] = vmrun_interception,
[SVM_EXIT_VMMCALL] = vmmcall_interception,
[SVM_EXIT_VMLOAD] = vmload_interception,
[SVM_EXIT_VMSAVE] = vmsave_interception,
@@ -1923,7 +2116,8 @@ static void svm_vcpu_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
svm->host_cr2 = kvm_read_cr2();
svm->host_dr6 = read_dr6();
svm->host_dr7 = read_dr7();
- svm->vmcb->save.cr2 = vcpu->arch.cr2;
+ if (!is_nested(svm))
+ svm->vmcb->save.cr2 = vcpu->arch.cr2;
/* required for live migration with NPT */
if (npt_enabled)
svm->vmcb->save.cr3 = vcpu->arch.cr3;
diff --git a/include/asm-x86/kvm_host.h b/include/asm-x86/kvm_host.h
index 3e25004..ad2ad32 100644
--- a/include/asm-x86/kvm_host.h
+++ b/include/asm-x86/kvm_host.h
@@ -736,6 +736,7 @@ enum {
};

#define HF_GIF_MASK (1 << 0)
+#define HF_HIF_MASK (1 << 1)

/*
* Hardware virtualization extension instructions may fault if a
--
1.5.6