[PATCH 8/8] kvm x86: report 1GB page support to userspace

Joerg Roedel
2009-06-19T13:18:58Z

If userspace knows that the kernel part supports 1GB pages it can enable
the corresponding cpuid bit so that guests actually use GB pages.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
---
arch/x86/include/asm/kvm_host.h | 1 +
arch/x86/kvm/svm.c | 6 ++++++
arch/x86/kvm/vmx.c | 6 ++++++
arch/x86/kvm/x86.c | 3 ++-
4 files changed, 15 insertions(+), 1 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 26ea9b8..c120882 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -527,6 +527,7 @@ struct kvm_x86_ops {
int (*set_tss_addr)(struct kvm *kvm, unsigned int addr);
int (*get_tdp_level)(void);
u64 (*get_mt_mask)(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio);
+ bool (*gb_page_enable)(void);
};

extern struct kvm_x86_ops *kvm_x86_ops;
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index c283201..ccb75fb 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -2718,6 +2718,11 @@ static u64 svm_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio)
return 0;
}

+static bool svm_gb_page_enable(void)
+{
+ return npt_enabled;
+}
+
static struct kvm_x86_ops svm_x86_ops = {
.cpu_has_kvm_support = has_svm,
.disabled_by_bios = is_disabled,
@@ -2779,6 +2784,7 @@ static struct kvm_x86_ops svm_x86_ops = {
.set_tss_addr = svm_set_tss_addr,
.get_tdp_level = get_npt_level,
.get_mt_mask = svm_get_mt_mask,
+ .gb_page_enable = svm_gb_page_enable,
};

static int __init svm_init(void)
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 9332938..4418ba6 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -3891,6 +3891,11 @@ static u64 vmx_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio)
return ret;
}

+static bool vmx_gb_page_enable(void)
+{
+ return false;
+}
+
static struct kvm_x86_ops vmx_x86_ops = {
.cpu_has_kvm_support = cpu_has_kvm_support,
.disabled_by_bios = vmx_disabled_by_bios,
@@ -3950,6 +3955,7 @@ static struct kvm_x86_ops vmx_x86_ops = {
.set_tss_addr = vmx_set_tss_addr,
.get_tdp_level = get_ept_level,
.get_mt_mask = vmx_get_mt_mask,
+ .gb_page_enable = vmx_gb_page_enable,
};

static int __init vmx_init(void)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 71090d2..ddfb77e 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1371,6 +1371,7 @@ static void do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
u32 index, int *nent, int maxnent)
{
unsigned f_nx = is_efer_nx() ? F(NX) : 0;
+ unsigned f_gbpages = kvm_x86_ops->gb_page_enable() ? F(GBPAGES) : 0;
#ifdef CONFIG_X86_64
unsigned f_lm = F(LM);
#else
@@ -1395,7 +1396,7 @@ static void do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
F(MTRR) | F(PGE) | F(MCA) | F(CMOV) |
F(PAT) | F(PSE36) | 0 /* Reserved */ |
f_nx | 0 /* Reserved */ | F(MMXEXT) | F(MMX) |
- F(FXSR) | F(FXSR_OPT) | 0 /* GBPAGES */ | 0 /* RDTSCP */ |
+ F(FXSR) | F(FXSR_OPT) | f_gbpages | 0 /* RDTSCP */ |
0 /* Reserved */ | f_lm | F(3DNOWEXT) | F(3DNOW);
/* cpuid 1.ecx */
const u32 kvm_supported_word4_x86_features =
--
1.6.3.1