[PATCH] KVM: AMD SVM: 32-bit host support

From: Avi Kivity
Date: Sun Dec 10 2006 - 04:15:05 EST

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From: Anthony Liguori <anthony@xxxxxxxxxxxxx>

This patch enables kvm support for 32-bit AMD SVM hosts.

Signed-off-by: Anthony Liguori <anthony@xxxxxxxxxxxxx>
Signed-off-by: Avi Kivity <avi@xxxxxxxxxxxx>

Index: linux-2.6/drivers/kvm/kvm_svm.h
===================================================================
--- linux-2.6.orig/drivers/kvm/kvm_svm.h
+++ linux-2.6/drivers/kvm/kvm_svm.h
@@ -9,11 +9,13 @@
#include "kvm.h"

static const u32 host_save_msrs[] = {
+#ifdef __x86_64__
MSR_STAR, MSR_LSTAR, MSR_CSTAR, MSR_SYSCALL_MASK, MSR_KERNEL_GS_BASE,
+ MSR_FS_BASE, MSR_GS_BASE,
+#endif
MSR_IA32_SYSENTER_CS, MSR_IA32_SYSENTER_ESP, MSR_IA32_SYSENTER_EIP,
MSR_IA32_DEBUGCTLMSR, /*MSR_IA32_LASTBRANCHFROMIP,
MSR_IA32_LASTBRANCHTOIP, MSR_IA32_LASTINTFROMIP,MSR_IA32_LASTINTTOIP,*/
- MSR_FS_BASE, MSR_GS_BASE,
};

#define NR_HOST_SAVE_MSRS (sizeof(host_save_msrs) / sizeof(*host_save_msrs))
Index: linux-2.6/drivers/kvm/svm.c
===================================================================
--- linux-2.6.orig/drivers/kvm/svm.c
+++ linux-2.6/drivers/kvm/svm.c
@@ -39,16 +39,28 @@ MODULE_LICENSE("GPL");
#define SEG_TYPE_LDT 2
#define SEG_TYPE_BUSY_TSS16 3

+#define KVM_EFER_LMA (1 << 10)
+#define KVM_EFER_LME (1 << 8)
+
unsigned long iopm_base;
unsigned long msrpm_base;

+struct kvm_ldttss_desc {
+ u16 limit0;
+ u16 base0;
+ unsigned base1 : 8, type : 5, dpl : 2, p : 1;
+ unsigned limit1 : 4, zero0 : 3, g : 1, base2 : 8;
+ u32 base3;
+ u32 zero1;
+} __attribute__((packed));
+
struct svm_cpu_data {
int cpu;

uint64_t asid_generation;
uint32_t max_asid;
uint32_t next_asid;
- struct ldttss_desc *tss_desc;
+ struct kvm_ldttss_desc *tss_desc;

struct page *save_area;
};
@@ -156,7 +168,7 @@ static inline void write_dr7(unsigned lo

static inline int svm_is_long_mode(struct kvm_vcpu *vcpu)
{
- return vcpu->svm->vmcb->save.efer & EFER_LMA;
+ return vcpu->svm->vmcb->save.efer & KVM_EFER_LMA;
}

static inline void force_new_asid(struct kvm_vcpu *vcpu)
@@ -171,8 +183,8 @@ static inline void flush_guest_tlb(struc

static void svm_set_efer(struct kvm_vcpu *vcpu, u64 efer)
{
- if (!(efer & EFER_LMA))
- efer &= ~EFER_LME;
+ if (!(efer & KVM_EFER_LMA))
+ efer &= ~KVM_EFER_LME;

vcpu->svm->vmcb->save.efer = efer | MSR_EFER_SVME_MASK;
vcpu->shadow_efer = efer;
@@ -275,7 +287,11 @@ static void svm_hardware_enable(void *ga

struct svm_cpu_data *svm_data;
uint64_t efer;
+#ifdef __x86_64__
struct desc_ptr gdt_descr;
+#else
+ struct Xgt_desc_struct gdt_descr;
+#endif
struct desc_struct *gdt;
int me = raw_smp_processor_id();

@@ -297,7 +313,7 @@ static void svm_hardware_enable(void *ga

asm volatile ( "sgdt %0" : "=m"(gdt_descr) );
gdt = (struct desc_struct *)gdt_descr.address;
- svm_data->tss_desc = (struct ldttss_desc *)(gdt + GDT_ENTRY_TSS);
+ svm_data->tss_desc = (struct kvm_ldttss_desc *)(gdt + GDT_ENTRY_TSS);

rdmsrl(MSR_EFER, efer);
wrmsrl(MSR_EFER, efer | MSR_EFER_SVME_MASK);
@@ -381,6 +397,7 @@ static __init int svm_hardware_setup(voi
memset(msrpm_va, 0xff, PAGE_SIZE * (1 << MSRPM_ALLOC_ORDER));
msrpm_base = page_to_pfn(msrpm_pages) << PAGE_SHIFT;

+#ifdef __x86_64__
set_msr_interception(msrpm_va, MSR_GS_BASE, 1, 1);
set_msr_interception(msrpm_va, MSR_FS_BASE, 1, 1);
set_msr_interception(msrpm_va, MSR_KERNEL_GS_BASE, 1, 1);
@@ -388,6 +405,7 @@ static __init int svm_hardware_setup(voi
set_msr_interception(msrpm_va, MSR_LSTAR, 1, 1);
set_msr_interception(msrpm_va, MSR_CSTAR, 1, 1);
set_msr_interception(msrpm_va, MSR_SYSCALL_MASK, 1, 1);
+#endif
set_msr_interception(msrpm_va, MSR_IA32_SYSENTER_CS, 1, 1);
set_msr_interception(msrpm_va, MSR_IA32_SYSENTER_ESP, 1, 1);
set_msr_interception(msrpm_va, MSR_IA32_SYSENTER_EIP, 1, 1);
@@ -687,15 +705,15 @@ static void svm_set_gdt(struct kvm_vcpu
static void svm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0)
{
#ifdef __x86_64__
- if (vcpu->shadow_efer & EFER_LME) {
+ if (vcpu->shadow_efer & KVM_EFER_LME) {
if (!is_paging(vcpu) && (cr0 & CR0_PG_MASK)) {
- vcpu->shadow_efer |= EFER_LMA;
- vcpu->svm->vmcb->save.efer |= EFER_LMA | EFER_LME;
+ vcpu->shadow_efer |= KVM_EFER_LMA;
+ vcpu->svm->vmcb->save.efer |= KVM_EFER_LMA | KVM_EFER_LME;
}

if (is_paging(vcpu) && !(cr0 & CR0_PG_MASK) ) {
- vcpu->shadow_efer &= ~EFER_LMA;
- vcpu->svm->vmcb->save.efer &= ~(EFER_LMA | EFER_LME);
+ vcpu->shadow_efer &= ~KVM_EFER_LMA;
+ vcpu->svm->vmcb->save.efer &= ~(KVM_EFER_LMA | KVM_EFER_LME);
}
}
#endif
@@ -1079,6 +1097,7 @@ static int svm_get_msr(struct kvm_vcpu *
case MSR_IA32_APICBASE:
*data = vcpu->apic_base;
break;
+#ifdef __x86_64__
case MSR_STAR:
*data = vcpu->svm->vmcb->save.star;
break;
@@ -1088,6 +1107,13 @@ static int svm_get_msr(struct kvm_vcpu *
case MSR_CSTAR:
*data = vcpu->svm->vmcb->save.cstar;
break;
+ case MSR_KERNEL_GS_BASE:
+ *data = vcpu->svm->vmcb->save.kernel_gs_base;
+ break;
+ case MSR_SYSCALL_MASK:
+ *data = vcpu->svm->vmcb->save.sfmask;
+ break;
+#endif
case MSR_IA32_SYSENTER_CS:
*data = vcpu->svm->vmcb->save.sysenter_cs;
break;
@@ -1097,12 +1123,6 @@ static int svm_get_msr(struct kvm_vcpu *
case MSR_IA32_SYSENTER_ESP:
*data = vcpu->svm->vmcb->save.sysenter_esp;
break;
- case MSR_KERNEL_GS_BASE:
- *data = vcpu->svm->vmcb->save.kernel_gs_base;
- break;
- case MSR_SYSCALL_MASK:
- *data = vcpu->svm->vmcb->save.sfmask;
- break;
default:
printk(KERN_ERR "kvm: unhandled rdmsr: 0x%x\n", ecx);
return 1;
@@ -1152,6 +1172,7 @@ static int svm_set_msr(struct kvm_vcpu *
case MSR_IA32_APICBASE:
vcpu->apic_base = data;
break;
+#ifdef __x86_64___
case MSR_STAR:
vcpu->svm->vmcb->save.star = data;
break;
@@ -1161,6 +1182,13 @@ static int svm_set_msr(struct kvm_vcpu *
case MSR_CSTAR:
vcpu->svm->vmcb->save.cstar = data;
break;
+ case MSR_KERNEL_GS_BASE:
+ vcpu->svm->vmcb->save.kernel_gs_base = data;
+ break;
+ case MSR_SYSCALL_MASK:
+ vcpu->svm->vmcb->save.sfmask = data;
+ break;
+#endif
case MSR_IA32_SYSENTER_CS:
vcpu->svm->vmcb->save.sysenter_cs = data;
break;
@@ -1170,12 +1198,6 @@ static int svm_set_msr(struct kvm_vcpu *
case MSR_IA32_SYSENTER_ESP:
vcpu->svm->vmcb->save.sysenter_esp = data;
break;
- case MSR_KERNEL_GS_BASE:
- vcpu->svm->vmcb->save.kernel_gs_base = data;
- break;
- case MSR_SYSCALL_MASK:
- vcpu->svm->vmcb->save.sfmask = data;
- break;
default:
printk(KERN_ERR "kvm: unhandled wrmsr: %x\n", ecx);
return 1;
@@ -1323,6 +1345,7 @@ static void kvm_reput_irq(struct kvm_vcp

static void save_db_regs(unsigned long *db_regs)
{
+#ifdef __x86_64__
asm ("mov %%dr0, %%rax \n\t"
"mov %%rax, %[dr0] \n\t"
"mov %%dr1, %%rax \n\t"
@@ -1336,6 +1359,21 @@ static void save_db_regs(unsigned long *
[dr2] "=m"(db_regs[2]),
[dr3] "=m"(db_regs[3])
: : "rax");
+#else
+ asm ("mov %%dr0, %%eax \n\t"
+ "mov %%eax, %[dr0] \n\t"
+ "mov %%dr1, %%eax \n\t"
+ "mov %%eax, %[dr1] \n\t"
+ "mov %%dr2, %%eax \n\t"
+ "mov %%eax, %[dr2] \n\t"
+ "mov %%dr3, %%eax \n\t"
+ "mov %%eax, %[dr3] \n\t"
+ : [dr0] "=m"(db_regs[0]),
+ [dr1] "=m"(db_regs[1]),
+ [dr2] "=m"(db_regs[2]),
+ [dr3] "=m"(db_regs[3])
+ : : "eax");
+#endif
}

static void load_db_regs(unsigned long *db_regs)
@@ -1349,7 +1387,11 @@ static void load_db_regs(unsigned long *
[dr1] "r"(db_regs[1]),
[dr2] "r"(db_regs[2]),
[dr3] "r"(db_regs[3])
+#ifdef __x86_64__
: "rax");
+#else
+ : "eax");
+#endif
}

static int svm_vcpu_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
@@ -1414,6 +1456,7 @@ again:
"mov %c[rbp](%[vcpu]), %%ebp \n\t"
#endif

+#ifdef __x86_64__
/* Enter guest mode */
"push %%rax \n\t"
"mov %c[svm](%[vcpu]), %%rax \n\t"
@@ -1422,6 +1465,16 @@ again:
SVM_VMRUN "\n\t"
SVM_VMSAVE "\n\t"
"pop %%rax \n\t"
+#else
+ /* Enter guest mode */
+ "push %%eax \n\t"
+ "mov %c[svm](%[vcpu]), %%eax \n\t"
+ "mov %c[vmcb](%%eax), %%eax \n\t"
+ SVM_VMLOAD "\n\t"
+ SVM_VMRUN "\n\t"
+ SVM_VMSAVE "\n\t"
+ "pop %%eax \n\t"
+#endif

/* Save guest registers, load host registers */
#ifdef __x86_64__
@@ -1445,12 +1498,12 @@ again:
"pop %%rbp; pop %%rdi; pop %%rsi;"
"pop %%rdx; pop %%rcx; pop %%rbx; \n\t"
#else
- "mov %%ebx, %c[rbx](%3) \n\t"
- "mov %%ecx, %c[rcx](%3) \n\t"
- "mov %%edx, %c[rdx](%3) \n\t"
- "mov %%esi, %c[rsi](%3) \n\t"
- "mov %%edi, %c[rdi](%3) \n\t"
- "mov %%ebp, %c[rbp](%3) \n\t"
+ "mov %%ebx, %c[rbx](%[vcpu]) \n\t"
+ "mov %%ecx, %c[rcx](%[vcpu]) \n\t"
+ "mov %%edx, %c[rdx](%[vcpu]) \n\t"
+ "mov %%esi, %c[rsi](%[vcpu]) \n\t"
+ "mov %%edi, %c[rdi](%[vcpu]) \n\t"
+ "mov %%ebp, %c[rbp](%[vcpu]) \n\t"

"pop %%ebp; pop %%edi; pop %%esi;"
"pop %%edx; pop %%ecx; pop %%ebx; \n\t"
Index: linux-2.6/drivers/kvm/Kconfig
===================================================================
--- linux-2.6.orig/drivers/kvm/Kconfig
+++ linux-2.6/drivers/kvm/Kconfig
@@ -27,7 +27,7 @@ config KVM_INTEL

config KVM_AMD
tristate "KVM for AMD processors support"
- depends on KVM && X86_64
+ depends on KVM
---help---
Provides support for KVM on AMD processors equipped with the AMD-V
(SVM) extensions.
-
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Next message: Arjan van de Ven: "Re: PAE/NX without performance drain?"
Previous message: linux: "Re: single bit errors on files stored on USB-HDDs via USB2/usb_storage"
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