[PATCH 4.9 065/107] x86/KVM/VMX: Separate the VMX AUTOLOAD guest/host number accounting

From: Greg Kroah-Hartman
Date: Tue Aug 14 2018 - 13:42:43 EST


4.9-stable review patch. If anyone has any objections, please let me know.

------------------

From: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>

commit 3190709335dd31fe1aeeebfe4ffb6c7624ef971f upstream

This allows to load a different number of MSRs depending on the context:
VMEXIT or VMENTER.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: David Woodhouse <dwmw@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kvm/vmx.c | 29 +++++++++++++++++++----------
1 file changed, 19 insertions(+), 10 deletions(-)

--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -2011,12 +2011,18 @@ static void clear_atomic_switch_msr(stru
}
i = find_msr(&m->guest, msr);
if (i < 0)
- return;
+ goto skip_guest;
--m->guest.nr;
- --m->host.nr;
m->guest.val[i] = m->guest.val[m->guest.nr];
- m->host.val[i] = m->host.val[m->host.nr];
vmcs_write32(VM_ENTRY_MSR_LOAD_COUNT, m->guest.nr);
+
+skip_guest:
+ i = find_msr(&m->host, msr);
+ if (i < 0)
+ return;
+
+ --m->host.nr;
+ m->host.val[i] = m->host.val[m->host.nr];
vmcs_write32(VM_EXIT_MSR_LOAD_COUNT, m->host.nr);
}

@@ -2034,7 +2040,7 @@ static void add_atomic_switch_msr_specia
static void add_atomic_switch_msr(struct vcpu_vmx *vmx, unsigned msr,
u64 guest_val, u64 host_val)
{
- int i;
+ int i, j;
struct msr_autoload *m = &vmx->msr_autoload;

switch (msr) {
@@ -2070,21 +2076,24 @@ static void add_atomic_switch_msr(struct
}

i = find_msr(&m->guest, msr);
- if (i == NR_AUTOLOAD_MSRS) {
+ j = find_msr(&m->host, msr);
+ if (i == NR_AUTOLOAD_MSRS || j == NR_AUTOLOAD_MSRS) {
printk_once(KERN_WARNING "Not enough msr switch entries. "
"Can't add msr %x\n", msr);
return;
- } else if (i < 0) {
+ }
+ if (i < 0) {
i = m->guest.nr++;
- ++m->host.nr;
vmcs_write32(VM_ENTRY_MSR_LOAD_COUNT, m->guest.nr);
+ }
+ if (j < 0) {
+ j = m->host.nr++;
vmcs_write32(VM_EXIT_MSR_LOAD_COUNT, m->host.nr);
}
-
m->guest.val[i].index = msr;
m->guest.val[i].value = guest_val;
- m->host.val[i].index = msr;
- m->host.val[i].value = host_val;
+ m->host.val[j].index = msr;
+ m->host.val[j].value = host_val;
}

static void reload_tss(void)