When the host enables XSAVE/XRSTOR, the patch exposes the XSAVE/XRSTOR
related CPUID leaves to guest by fixing up kvm_emulate_cpuid() and the
patch allows guest to set CR4.OSXSAVE to enable XSAVE.
The patch adds per-vcpu host/guest xstate image/mask and enhances the
current FXSAVE/FRSTOR with the new XSAVE/XRSTOR on the host xstate
(FPU/SSE/YMM) switch.
Signed-off-by: Dexuan Cui <dexuan....@intel.com>
---
arch/x86/include/asm/kvm_host.h | 15 +--
arch/x86/include/asm/vmx.h | 1 +
arch/x86/include/asm/xsave.h | 3 +
arch/x86/kvm/vmx.c | 24 +++++
arch/x86/kvm/x86.c | 217 +++++++++++++++++++++++++++++++++++++--
5 files changed, 242 insertions(+), 18 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 3f0007b..60be1a7 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -303,6 +303,11 @@ struct kvm_vcpu_arch {
struct i387_fxsave_struct host_fx_image;
struct i387_fxsave_struct guest_fx_image;
+ struct xsave_struct *host_xstate_image;
+ struct xsave_struct *guest_xstate_image;
+ uint64_t host_xstate_mask;
+ uint64_t guest_xstate_mask;
+
gva_t mmio_fault_cr2;
struct kvm_pio_request pio;
void *pio_data;
@@ -718,16 +723,6 @@ static inline unsigned long read_msr(unsigned long msr)
}
#endif
-static inline void kvm_fx_save(struct i387_fxsave_struct *image)
-{
- asm("fxsave (%0)":: "r" (image));
-}
-
-static inline void kvm_fx_restore(struct i387_fxsave_struct *image)
-{
- asm("fxrstor (%0)":: "r" (image));
-}
-
static inline void kvm_fx_finit(void)
{
asm("finit");
diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
index fb9a080..842286b 100644
--- a/arch/x86/include/asm/vmx.h
+++ b/arch/x86/include/asm/vmx.h
@@ -260,6 +260,7 @@ enum vmcs_field {
#define EXIT_REASON_EPT_VIOLATION 48
#define EXIT_REASON_EPT_MISCONFIG 49
#define EXIT_REASON_WBINVD 54
+#define EXIT_REASON_XSETBV 55
/*
* Interruption-information format
diff --git a/arch/x86/include/asm/xsave.h b/arch/x86/include/asm/xsave.h
index ddc04cc..ada81a2 100644
--- a/arch/x86/include/asm/xsave.h
+++ b/arch/x86/include/asm/xsave.h
@@ -13,6 +13,9 @@
#define FXSAVE_SIZE 512
+#define XSTATE_YMM_SIZE 256
+#define XSTATE_YMM_OFFSET (512 + 64)
+
/*
* These are the features that the OS can handle currently.
*/
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 875b785..a72d024 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -35,6 +35,8 @@
#include <asm/vmx.h>
#include <asm/virtext.h>
#include <asm/mce.h>
+#include <asm/i387.h>
+#include <asm/xcr.h>
#include "trace.h"
@@ -2517,6 +2519,8 @@ static int vmx_vcpu_setup(struct vcpu_vmx *vmx)
vmx->vcpu.arch.cr4_guest_owned_bits = KVM_CR4_GUEST_OWNED_BITS;
if (enable_ept)
vmx->vcpu.arch.cr4_guest_owned_bits |= X86_CR4_PGE;
+ if (cpu_has_xsave)
+ vmx->vcpu.arch.cr4_guest_owned_bits |= X86_CR4_OSXSAVE;
vmcs_writel(CR4_GUEST_HOST_MASK, ~vmx->vcpu.arch.cr4_guest_owned_bits);
tsc_base = vmx->vcpu.kvm->arch.vm_init_tsc;
@@ -3258,6 +3262,25 @@ static int handle_wbinvd(struct kvm_vcpu *vcpu)
return 1;
}
+static int handle_xsetbv(struct kvm_vcpu *vcpu)
+{
+ u64 new_bv = ((u64)kvm_register_read(vcpu, VCPU_REGS_RDX)) |
+ kvm_register_read(vcpu, VCPU_REGS_RAX);
+ u64 host_bv = vcpu->arch.host_xstate_mask;
+
+ if (((new_bv ^ host_bv) & ~host_bv) || !(new_bv & 1))
+ goto err;
+ if ((host_bv & XSTATE_YMM & new_bv) && !(new_bv & XSTATE_SSE))
+ goto err;
+ vcpu->arch.guest_xstate_mask = new_bv;
+ xsetbv(XCR_XFEATURE_ENABLED_MASK, vcpu->arch.guest_xstate_mask);
+ skip_emulated_instruction(vcpu);
+ return 1;
+err:
+ kvm_inject_gp(vcpu, 0);
+ return 1;
+}
+
static int handle_apic_access(struct kvm_vcpu *vcpu)
{
unsigned long exit_qualification;
@@ -3556,6 +3579,7 @@ static int (*kvm_vmx_exit_handlers[])(struct kvm_vcpu
*vcpu) = {
[EXIT_REASON_TPR_BELOW_THRESHOLD] = handle_tpr_below_threshold,
[EXIT_REASON_APIC_ACCESS] = handle_apic_access,
[EXIT_REASON_WBINVD] = handle_wbinvd,
+ [EXIT_REASON_XSETBV] = handle_xsetbv,
[EXIT_REASON_TASK_SWITCH] = handle_task_switch,
[EXIT_REASON_MCE_DURING_VMENTRY] = handle_machine_check,
[EXIT_REASON_EPT_VIOLATION] = handle_ept_violation,
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 6b2ce1d..2af3fbe 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -52,6 +52,8 @@
#include <asm/desc.h>
#include <asm/mtrr.h>
#include <asm/mce.h>
+#include <asm/i387.h>
+#include <asm/xcr.h>
#define MAX_IO_MSRS 256
#define CR0_RESERVED_BITS \
@@ -62,6 +64,7 @@
(~(unsigned long)(X86_CR4_VME | X86_CR4_PVI | X86_CR4_TSD | X86_CR4_DE\
| X86_CR4_PSE | X86_CR4_PAE | X86_CR4_MCE \
| X86_CR4_PGE | X86_CR4_PCE | X86_CR4_OSFXSR \
+ | (cpu_has_xsave ? X86_CR4_OSXSAVE : 0) \
| X86_CR4_OSXMMEXCPT | X86_CR4_VMXE))
#define CR8_RESERVED_BITS (~(unsigned long)X86_CR8_TPR)
@@ -4017,6 +4020,36 @@ void kvm_after_handle_nmi(struct kvm_vcpu *vcpu)
}
EXPORT_SYMBOL_GPL(kvm_after_handle_nmi);
+static struct kmem_cache *kvm_xstate_cachep;
+static unsigned int kvm_xstate_size;
+
+static int kvm_alloc_xstate_cachep(void)
+{
+ u32 eax, ebx, ecx, edx;
+
+ if (!cpu_has_xsave)
+ return 0;
+
+ cpuid_count(0xd, 0, &eax, &ebx, &ecx, &edx);
+ kvm_xstate_size = ebx;
+ kvm_xstate_cachep =
+ kmem_cache_create("kvm_vcpu_xstate", kvm_xstate_size,
+ __alignof__(union thread_xstate), 0, NULL);
+ if (!kvm_xstate_cachep)
+ return -ENOMEM;
+
+ return 0;
+}
+
+static void kvm_free_xstate_cachep(void)
+{
+ if (!kvm_xstate_cachep)
+ return;
+
+ kmem_cache_destroy(kvm_xstate_cachep);
+ kvm_xstate_cachep = NULL;
+}
+
int kvm_arch_init(void *opaque)
{
int r;
@@ -4039,6 +4072,10 @@ int kvm_arch_init(void *opaque)
goto out;
}
+ r = kvm_alloc_xstate_cachep();
+ if (r)
+ goto out;
+
r = kvm_mmu_module_init();
if (r)
goto out;
@@ -4058,6 +4095,7 @@ int kvm_arch_init(void *opaque)
return 0;
out:
+ kvm_free_xstate_cachep();
return r;
}
@@ -4070,6 +4108,7 @@ void kvm_arch_exit(void)
CPUFREQ_TRANSITION_NOTIFIER);
kvm_x86_ops = NULL;
kvm_mmu_module_exit();
+ kvm_free_xstate_cachep();
}
int kvm_emulate_halt(struct kvm_vcpu *vcpu)
@@ -4307,6 +4346,65 @@ not_found:
return 36;
}
+#define bitmaskof(idx) (1U << ((idx) & 31))
+static void kvm_emulate_cpuid_fixup(struct kvm_vcpu *vcpu, u32 func, u32 idx)
+{
+ u32 eax, ebx, ecx, edx;
+
+ if (func != 0 && func != 1 && func != 0xd)
+ return;
+
+ eax = kvm_register_read(vcpu, VCPU_REGS_RAX);
+ ebx = kvm_register_read(vcpu, VCPU_REGS_RBX);
+ ecx = kvm_register_read(vcpu, VCPU_REGS_RCX);
+ edx = kvm_register_read(vcpu, VCPU_REGS_RDX);
+
+ switch (func) {
+ case 0:
+ /* fixup the Maximum Input Value */
+ if (cpu_has_xsave && eax < 0xd)
+ eax = 0xd;
+ break;
+ case 1:
+ ecx &= ~(bitmaskof(X86_FEATURE_XSAVE) |
+ bitmaskof(X86_FEATURE_OSXSAVE));
+ if (!cpu_has_xsave)
+ break;
+ ecx |= bitmaskof(X86_FEATURE_XSAVE);
+ if (kvm_read_cr4(vcpu) & X86_CR4_OSXSAVE)
+ ecx |= bitmaskof(X86_FEATURE_OSXSAVE);
+ break;
+ case 0xd:
+ eax = ebx = ecx = edx = 0;
+ if (!cpu_has_xsave)
+ break;
+ switch (idx) {
+ case 0:
+ eax = vcpu->arch.host_xstate_mask & XCNTXT_MASK;
+ /* FP/SSE + XSAVE.HEADER + YMM. */
+ ecx = 512 + 64;
+ if (eax & XSTATE_YMM)
+ ecx += XSTATE_YMM_SIZE;
+ ebx = ecx;
+ break;
+ case 2:
+ if (!(vcpu->arch.host_xstate_mask & XSTATE_YMM))
+ break;
+ eax = XSTATE_YMM_SIZE;
+ ebx = XSTATE_YMM_OFFSET;
+ break;
+ default:
+ break;
+ }
+ break;
+ }
+
+ kvm_register_write(vcpu, VCPU_REGS_RAX, eax);
+ kvm_register_write(vcpu, VCPU_REGS_RBX, ebx);
+ kvm_register_write(vcpu, VCPU_REGS_RCX, ecx);
+ kvm_register_write(vcpu, VCPU_REGS_RDX, edx);
+}
+
void kvm_emulate_cpuid(struct kvm_vcpu *vcpu)
{
u32 function, index;
@@ -4325,6 +4423,9 @@ void kvm_emulate_cpuid(struct kvm_vcpu *vcpu)
kvm_register_write(vcpu, VCPU_REGS_RCX, best->ecx);
kvm_register_write(vcpu, VCPU_REGS_RDX, best->edx);
}
+
+ kvm_emulate_cpuid_fixup(vcpu, function, index);
+
kvm_x86_ops->skip_emulated_instruction(vcpu);
trace_kvm_cpuid(function,
kvm_register_read(vcpu, VCPU_REGS_RAX),
@@ -5091,6 +5192,60 @@ int kvm_arch_vcpu_ioctl_set_fpu(struct kvm_vcpu *vcpu,
struct kvm_fpu *fpu)
return 0;
}
+#ifdef CONFIG_X86_64
+#define REX_PREFIX "0x48, "
+#else
+#define REX_PREFIX
+#endif
+
+static inline void kvm_fx_save_host(struct kvm_vcpu *vcpu)
+{
+ if (cpu_has_xsave) {
+ asm volatile (".byte " REX_PREFIX "0x0f,0xae,0x27"
+ : : "a" (-1), "d" (-1), "D"(vcpu->arch.host_xstate_image)
+ : "memory");
+ vcpu->arch.host_xstate_mask =
+ xgetbv(XCR_XFEATURE_ENABLED_MASK);
+ } else {
+ asm("fxsave (%0)" : : "r" (&vcpu->arch.host_fx_image));
+ }
+}
+
+static inline void kvm_fx_save_guest(struct kvm_vcpu *vcpu)
+{
+ if (cpu_has_xsave) {
+ asm volatile (".byte " REX_PREFIX "0x0f,0xae,0x27"
+ : : "a" (-1), "d" (-1), "D"(vcpu->arch.guest_xstate_image)
+ : "memory");
+ vcpu->arch.guest_xstate_mask =
+ xgetbv(XCR_XFEATURE_ENABLED_MASK);
+ } else {
+ asm("fxsave (%0)" : : "r" (&vcpu->arch.guest_fx_image));
+ }
+}
+
+static inline void kvm_fx_restore_host(struct kvm_vcpu *vcpu)
+{
+ if (cpu_has_xsave) {
+ xsetbv(XCR_XFEATURE_ENABLED_MASK, vcpu->arch.host_xstate_mask);
+ asm volatile (".byte " REX_PREFIX "0x0f,0xae,0x2f"
+ : : "a" (-1), "d" (-1), "D"(vcpu->arch.host_xstate_image));
+ } else {
+ asm("fxrstor (%0)" : : "r" (&vcpu->arch.host_fx_image));
+ }
+}
+
+static inline void kvm_fx_restore_guest(struct kvm_vcpu *vcpu)
+{
+ if (cpu_has_xsave) {
+ xsetbv(XCR_XFEATURE_ENABLED_MASK, vcpu->arch.guest_xstate_mask);
+ asm volatile (".byte " REX_PREFIX "0x0f,0xae,0x2f"
+ : : "a" (-1), "d" (-1), "D"(vcpu->arch.guest_xstate_image));
+ } else {
+ asm("fxrstor (%0)" : : "r" (&vcpu->arch.guest_fx_image));
+ }
+}
+
void fx_init(struct kvm_vcpu *vcpu)
{
unsigned after_mxcsr_mask;
@@ -5102,17 +5257,21 @@ void fx_init(struct kvm_vcpu *vcpu)
* allocate ram with GFP_KERNEL.
*/
if (!used_math())
- kvm_fx_save(&vcpu->arch.host_fx_image);
+ kvm_fx_save_host(vcpu);
/* Initialize guest FPU by resetting ours and saving into guest's */
preempt_disable();
- kvm_fx_save(&vcpu->arch.host_fx_image);
+ kvm_fx_save_host(vcpu);
kvm_fx_finit();
- kvm_fx_save(&vcpu->arch.guest_fx_image);
- kvm_fx_restore(&vcpu->arch.host_fx_image);
+ kvm_fx_save_guest(vcpu);
+ kvm_fx_restore_host(vcpu);
preempt_enable();
vcpu->arch.cr0 |= X86_CR0_ET;
+
+ if (cpu_has_xsave)
+ return;
+
after_mxcsr_mask = offsetof(struct i387_fxsave_struct, st_space);
vcpu->arch.guest_fx_image.mxcsr = 0x1f80;
memset((void *)&vcpu->arch.guest_fx_image + after_mxcsr_mask,
@@ -5126,8 +5285,8 @@ void kvm_load_guest_fpu(struct kvm_vcpu *vcpu)
return;
vcpu->guest_fpu_loaded = 1;
- kvm_fx_save(&vcpu->arch.host_fx_image);
- kvm_fx_restore(&vcpu->arch.guest_fx_image);
+ kvm_fx_save_host(vcpu);
+ kvm_fx_restore_guest(vcpu);
trace_kvm_fpu(1);
}
@@ -5137,13 +5296,50 @@ void kvm_put_guest_fpu(struct kvm_vcpu *vcpu)
return;
vcpu->guest_fpu_loaded = 0;
- kvm_fx_save(&vcpu->arch.guest_fx_image);
- kvm_fx_restore(&vcpu->arch.host_fx_image);
+ kvm_fx_save_guest(vcpu);
+ kvm_fx_restore_host(vcpu);
++vcpu->stat.fpu_reload;
set_bit(KVM_REQ_DEACTIVATE_FPU, &vcpu->requests);
trace_kvm_fpu(0);
}
+static void kvm_arch_vcpu_destroy_xstate_image(struct kvm_vcpu *vcpu)
+{
+ if (vcpu->arch.guest_xstate_image)
+ kmem_cache_free(kvm_xstate_cachep,
+ vcpu->arch.guest_xstate_image);
+ if (vcpu->arch.host_xstate_image)
+ kmem_cache_free(kvm_xstate_cachep,
+ vcpu->arch.host_xstate_image);
+ vcpu->arch.guest_xstate_image = NULL;
+ vcpu->arch.host_xstate_image = NULL;
+}
+
+static int kvm_arch_vcpu_create_xstate_image(struct kvm_vcpu *vcpu)
+{
+ if (!cpu_has_xsave)
+ return 0;
+
+ if (!vcpu->arch.guest_xstate_image) {
+ vcpu->arch.guest_xstate_image =
+ kmem_cache_zalloc(kvm_xstate_cachep, GFP_KERNEL);
+ if (!vcpu->arch.guest_xstate_image)
+ goto err;
+ }
+ if (!vcpu->arch.host_xstate_image) {
+ vcpu->arch.host_xstate_image =
+ kmem_cache_zalloc(kvm_xstate_cachep, GFP_KERNEL);
+ if (!vcpu->arch.host_xstate_image)
+ goto err;
+ }
+
+ return 0;
+
+err:
+ kvm_arch_vcpu_destroy_xstate_image(vcpu);
+ return -ENOMEM;
+}
+
void kvm_arch_vcpu_free(struct kvm_vcpu *vcpu)
{
if (vcpu->arch.time_page) {
@@ -5152,6 +5348,7 @@ void kvm_arch_vcpu_free(struct kvm_vcpu *vcpu)
}
kvm_x86_ops->vcpu_free(vcpu);
+ kvm_arch_vcpu_destroy_xstate_image(vcpu);
}
struct kvm_vcpu *kvm_arch_vcpu_create(struct kvm *kvm,
@@ -5189,6 +5386,7 @@ void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu)
vcpu_put(vcpu);
kvm_x86_ops->vcpu_free(vcpu);
+ kvm_arch_vcpu_destroy_xstate_image(vcpu);
}
int kvm_arch_vcpu_reset(struct kvm_vcpu *vcpu)
@@ -5201,6 +5399,9 @@ int kvm_arch_vcpu_reset(struct kvm_vcpu *vcpu)
vcpu->arch.dr6 = DR6_FIXED_1;
vcpu->arch.dr7 = DR7_FIXED_1;
+ if (kvm_arch_vcpu_create_xstate_image(vcpu) < 0)
+ return -ENOMEM;
+
return kvm_x86_ops->vcpu_reset(vcpu);
}
--
1.6.0
--
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