[RFCv2 02/13] x86/kvm: Introduce KVM memory protection feature

Kirill A. Shutemov
2021-04-16T15:41:41Z

Provide basic helpers, KVM_FEATURE, CPUID flag and a hypercall.

Host side doesn't provide the feature yet, so it is a dead code for now.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
arch/x86/include/asm/cpufeatures.h | 1 +
arch/x86/include/asm/kvm_para.h | 5 +++++
arch/x86/include/uapi/asm/kvm_para.h | 3 ++-
arch/x86/kernel/kvm.c | 17 +++++++++++++++++
include/uapi/linux/kvm_para.h | 3 ++-
5 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index 84b887825f12..d8f3d2619913 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -238,6 +238,7 @@
#define X86_FEATURE_VMW_VMMCALL ( 8*32+19) /* "" VMware prefers VMMCALL hypercall instruction */
#define X86_FEATURE_SEV_ES ( 8*32+20) /* AMD Secure Encrypted Virtualization - Encrypted State */
#define X86_FEATURE_VM_PAGE_FLUSH ( 8*32+21) /* "" VM Page Flush MSR is supported */
+#define X86_FEATURE_KVM_MEM_PROTECTED ( 8*32+22) /* "" KVM memory protection extension */

/* Intel-defined CPU features, CPUID level 0x00000007:0 (EBX), word 9 */
#define X86_FEATURE_FSGSBASE ( 9*32+ 0) /* RDFSBASE, WRFSBASE, RDGSBASE, WRGSBASE instructions*/
diff --git a/arch/x86/include/asm/kvm_para.h b/arch/x86/include/asm/kvm_para.h
index 338119852512..74aea18f3130 100644
--- a/arch/x86/include/asm/kvm_para.h
+++ b/arch/x86/include/asm/kvm_para.h
@@ -11,11 +11,16 @@ extern void kvmclock_init(void);

#ifdef CONFIG_KVM_GUEST
bool kvm_check_and_clear_guest_paused(void);
+bool kvm_mem_protected(void);
#else
static inline bool kvm_check_and_clear_guest_paused(void)
{
return false;
}
+static inline bool kvm_mem_protected(void)
+{
+ return false;
+}
#endif /* CONFIG_KVM_GUEST */

#define KVM_HYPERCALL \
diff --git a/arch/x86/include/uapi/asm/kvm_para.h b/arch/x86/include/uapi/asm/kvm_para.h
index 950afebfba88..8d32c41861c9 100644
--- a/arch/x86/include/uapi/asm/kvm_para.h
+++ b/arch/x86/include/uapi/asm/kvm_para.h
@@ -28,11 +28,12 @@
#define KVM_FEATURE_PV_UNHALT 7
#define KVM_FEATURE_PV_TLB_FLUSH 9
#define KVM_FEATURE_ASYNC_PF_VMEXIT 10
-#define KVM_FEATURE_PV_SEND_IPI 11
+#define KVM_FEATURE_PV_SEND_IPI 11
#define KVM_FEATURE_POLL_CONTROL 12
#define KVM_FEATURE_PV_SCHED_YIELD 13
#define KVM_FEATURE_ASYNC_PF_INT 14
#define KVM_FEATURE_MSI_EXT_DEST_ID 15
+#define KVM_FEATURE_MEM_PROTECTED 16

#define KVM_HINTS_REALTIME 0

diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index 5e78e01ca3b4..aed6034fcac1 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -39,6 +39,13 @@
#include <asm/ptrace.h>
#include <asm/svm.h>

+static bool mem_protected;
+
+bool kvm_mem_protected(void)
+{
+ return mem_protected;
+}
+
DEFINE_STATIC_KEY_FALSE(kvm_async_pf_enabled);

static int kvmapf = 1;
@@ -749,6 +756,16 @@ static void __init kvm_init_platform(void)
{
kvmclock_init();
x86_platform.apic_post_init = kvm_apic_init;
+
+ if (kvm_para_has_feature(KVM_FEATURE_MEM_PROTECTED)) {
+ if (kvm_hypercall0(KVM_HC_ENABLE_MEM_PROTECTED)) {
+ panic("Failed to enable KVM memory protection");
+ }
+
+ pr_info("KVM memory protection enabled\n");
+ mem_protected = true;
+ setup_force_cpu_cap(X86_FEATURE_KVM_MEM_PROTECTED);
+ }
}

#if defined(CONFIG_AMD_MEM_ENCRYPT)
diff --git a/include/uapi/linux/kvm_para.h b/include/uapi/linux/kvm_para.h
index 8b86609849b9..1a216f32e572 100644
--- a/include/uapi/linux/kvm_para.h
+++ b/include/uapi/linux/kvm_para.h
@@ -27,8 +27,9 @@
#define KVM_HC_MIPS_EXIT_VM 7
#define KVM_HC_MIPS_CONSOLE_OUTPUT 8
#define KVM_HC_CLOCK_PAIRING 9
-#define KVM_HC_SEND_IPI 10
+#define KVM_HC_SEND_IPI 10
#define KVM_HC_SCHED_YIELD 11
+#define KVM_HC_ENABLE_MEM_PROTECTED 12

/*
* hypercalls use architecture specific
--
2.26.3