To set up and run the confidential VMBus, the guest needs the paravisor
to intercept access to some synthetic MSRs. In the non-confidential case,
the guest continues using the vendor-specific guest-host communication
protocol.
Update the hv_set_non_nested_msr() function to trap access to some
synthetic MSRs.
Signed-off-by: Roman Kisel <romank@xxxxxxxxxxxxxxxxxxx>
Reviewed-by: Alok Tiwari <alok.a.tiwari@xxxxxxxxxx>
---
arch/x86/kernel/cpu/mshyperv.c | 23 +++++++++++++++++++----
1 file changed, 19 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index 83a85d94bcb3..db6f3e3db012 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -28,6 +28,7 @@
#include <asm/apic.h>
#include <asm/timer.h>
#include <asm/reboot.h>
+#include <asm/msr.h>
#include <asm/nmi.h>
#include <clocksource/hyperv_timer.h>
#include <asm/numa.h>
@@ -77,14 +78,28 @@ EXPORT_SYMBOL_GPL(hv_get_non_nested_msr);
void hv_set_non_nested_msr(unsigned int reg, u64 value)
{
+ if (reg == HV_X64_MSR_EOM && vmbus_is_confidential()) {
+ /* Reach out to the paravisor. */
+ native_wrmsrl(reg, value);
+ return;
+ }
+
if (hv_is_synic_msr(reg) && ms_hyperv.paravisor_present) {
+ /* The hypervisor will get the intercept. */
hv_ivm_msr_write(reg, value);
- /* Write proxy bit via wrmsl instruction */
- if (hv_is_sint_msr(reg))
- wrmsrl(reg, value | 1 << 20);
+ if (hv_is_sint_msr(reg)) {
+ /*
+ * Write proxy bit in the case of non-confidential VMBus.
+ * Using wrmsl instruction so the following goes to the paravisor.
+ */
+ u32 proxy = vmbus_is_confidential() ? 0 : 1;
+
+ value |= (proxy << 20);
+ native_wrmsrl(reg, value);
+ }
} else {
- wrmsrl(reg, value);
+ native_wrmsrl(reg, value);
}
}
EXPORT_SYMBOL_GPL(hv_set_non_nested_msr);
--
2.43.0
