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Subject[150/205] KVM: SVM: Implement workaround for Erratum 383
2.6.34-stable review patch.  If anyone has any objections, please let us know.

------------------
This patch implements a workaround for AMD erratum 383 into
KVM. Without this erratum fix it is possible for a guest to
kill the host machine. This patch implements the suggested
workaround for hypervisors which will be published by the
next revision guide update.

[jan: fix overflow warning on i386]
[xiao: fix unused variable warning]

Cc: stable@kernel.org
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
(cherry picked from commit 67ec66077799f2fef84b21a643912b179c422281)
---
arch/x86/include/asm/msr-index.h | 1
arch/x86/kvm/svm.c | 81 +++++++++++++++++++++++++++++++++++++++
2 files changed, 82 insertions(+)
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -107,6 +107,7 @@
#define MSR_AMD64_PATCH_LOADER 0xc0010020
#define MSR_AMD64_OSVW_ID_LENGTH 0xc0010140
#define MSR_AMD64_OSVW_STATUS 0xc0010141
+#define MSR_AMD64_DC_CFG 0xc0011022
#define MSR_AMD64_IBSFETCHCTL 0xc0011030
#define MSR_AMD64_IBSFETCHLINAD 0xc0011031
#define MSR_AMD64_IBSFETCHPHYSAD 0xc0011032
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -28,6 +28,7 @@
#include <linux/ftrace_event.h>
#include <linux/slab.h>

+#include <asm/tlbflush.h>
#include <asm/desc.h>

#include <asm/virtext.h>
@@ -55,6 +56,8 @@ MODULE_LICENSE("GPL");

#define DEBUGCTL_RESERVED_BITS (~(0x3fULL))

+static bool erratum_383_found __read_mostly;
+
static const u32 host_save_user_msrs[] = {
#ifdef CONFIG_X86_64
MSR_STAR, MSR_LSTAR, MSR_CSTAR, MSR_SYSCALL_MASK, MSR_KERNEL_GS_BASE,
@@ -298,6 +301,31 @@ static void skip_emulated_instruction(st
svm_set_interrupt_shadow(vcpu, 0);
}

+static void svm_init_erratum_383(void)
+{
+ u32 low, high;
+ int err;
+ u64 val;
+
+ /* Only Fam10h is affected */
+ if (boot_cpu_data.x86 != 0x10)
+ return;
+
+ /* Use _safe variants to not break nested virtualization */
+ val = native_read_msr_safe(MSR_AMD64_DC_CFG, &err);
+ if (err)
+ return;
+
+ val |= (1ULL << 47);
+
+ low = lower_32_bits(val);
+ high = upper_32_bits(val);
+
+ native_write_msr_safe(MSR_AMD64_DC_CFG, low, high);
+
+ erratum_383_found = true;
+}
+
static int has_svm(void)
{
const char *msg;
@@ -353,6 +381,8 @@ static int svm_hardware_enable(void *gar

wrmsrl(MSR_VM_HSAVE_PA, page_to_pfn(sd->save_area) << PAGE_SHIFT);

+ svm_init_erratum_383();
+
return 0;
}

@@ -1280,8 +1310,59 @@ static int nm_interception(struct vcpu_s
return 1;
}

+static bool is_erratum_383(void)
+{
+ int err, i;
+ u64 value;
+
+ if (!erratum_383_found)
+ return false;
+
+ value = native_read_msr_safe(MSR_IA32_MC0_STATUS, &err);
+ if (err)
+ return false;
+
+ /* Bit 62 may or may not be set for this mce */
+ value &= ~(1ULL << 62);
+
+ if (value != 0xb600000000010015ULL)
+ return false;
+
+ /* Clear MCi_STATUS registers */
+ for (i = 0; i < 6; ++i)
+ native_write_msr_safe(MSR_IA32_MCx_STATUS(i), 0, 0);
+
+ value = native_read_msr_safe(MSR_IA32_MCG_STATUS, &err);
+ if (!err) {
+ u32 low, high;
+
+ value &= ~(1ULL << 2);
+ low = lower_32_bits(value);
+ high = upper_32_bits(value);
+
+ native_write_msr_safe(MSR_IA32_MCG_STATUS, low, high);
+ }
+
+ /* Flush tlb to evict multi-match entries */
+ __flush_tlb_all();
+
+ return true;
+}
+
static void svm_handle_mce(struct vcpu_svm *svm)
{
+ if (is_erratum_383()) {
+ /*
+ * Erratum 383 triggered. Guest state is corrupt so kill the
+ * guest.
+ */
+ pr_err("KVM: Guest triggered AMD Erratum 383\n");
+
+ set_bit(KVM_REQ_TRIPLE_FAULT, &svm->vcpu.requests);
+
+ return;
+ }
+
/*
* On an #MC intercept the MCE handler is not called automatically in
* the host. So do it by hand here.



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