arch/x86: mshyperv: Trap on access for some synthetic MSRs

hv_set_non_nested_msr() has special handling for SINT MSRs
when a paravisor is present. In addition to updating the MSR on the
host, the mirror MSR in the paravisor is updated, including with the
proxy bit. But with Confidential VMBus, the proxy bit must not be
used, so add a special case to skip it.

Signed-off-by: Roman Kisel <romank@linux.microsoft.com>
Reviewed-by: Alok Tiwari <alok.a.tiwari@oracle.com>
Reviewed-by: Tianyu Lan <tiala@microsoft.com>
Reviewed-by: Michael Kelley <mhklinux@outlook.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>

diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index eb9f1d7eec61b5bb7238ff1fd1a9d984ce7a48ed..80a641a6ac48b5de2e5aae7386ea31bc3f241bc9 100644 (file)
--- 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/msr.h>
@@ -39,6 +40,12 @@ bool hv_nested;
 struct ms_hyperv_info ms_hyperv;
 
 #if IS_ENABLED(CONFIG_HYPERV)
+/*
+ * When running with the paravisor, controls proxying the synthetic interrupts
+ * from the host
+ */
+static bool hv_para_sint_proxy;
+
 static inline unsigned int hv_get_nested_msr(unsigned int reg)
 {
        if (hv_is_sint_msr(reg))
@@ -75,17 +82,31 @@ EXPORT_SYMBOL_GPL(hv_get_non_nested_msr);
 void hv_set_non_nested_msr(unsigned int reg, u64 value)
 {
        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))
-                       wrmsrq(reg, value | 1 << 20);
+               /* Using wrmsrq so the following goes to the paravisor. */
+               if (hv_is_sint_msr(reg)) {
+                       union hv_synic_sint sint = { .as_uint64 = value };
+
+                       sint.proxy = hv_para_sint_proxy;
+                       native_wrmsrq(reg, sint.as_uint64);
+               }
        } else {
-               wrmsrq(reg, value);
+               native_wrmsrq(reg, value);
        }
 }
 EXPORT_SYMBOL_GPL(hv_set_non_nested_msr);
 
+/*
+ * Enable or disable proxying synthetic interrupts
+ * to the paravisor.
+ */
+void hv_para_set_sint_proxy(bool enable)
+{
+       hv_para_sint_proxy = enable;
+}
+
 /*
  * Get the SynIC register value from the paravisor.
  */

diff --git a/drivers/hv/hv_common.c b/drivers/hv/hv_common.c
index c39472ae8345a78a193fd28c35f9a2f46e9b521c..4b44da7f23b27ef2c5de3f1e9c94ffdb544c0d99 100644 (file)
--- a/drivers/hv/hv_common.c
+++ b/drivers/hv/hv_common.c
@@ -721,6 +721,11 @@ void __weak hv_enable_coco_interrupt(unsigned int cpu, unsigned int vector, bool
 }
 EXPORT_SYMBOL_GPL(hv_enable_coco_interrupt);
 
+void __weak hv_para_set_sint_proxy(bool enable)
+{
+}
+EXPORT_SYMBOL_GPL(hv_para_set_sint_proxy);
+
 u64 __weak hv_para_get_synic_register(unsigned int reg)
 {
        return ~0ULL;

diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h
index c328265de62446c91ecd5a7005ad508aa286574a..ecedab554c80d01178c8b2d265e79f05ae3d497c 100644 (file)
--- a/include/asm-generic/mshyperv.h
+++ b/include/asm-generic/mshyperv.h
@@ -310,6 +310,7 @@ bool hv_isolation_type_snp(void);
 u64 hv_ghcb_hypercall(u64 control, void *input, void *output, u32 input_size);
 u64 hv_tdx_hypercall(u64 control, u64 param1, u64 param2);
 void hv_enable_coco_interrupt(unsigned int cpu, unsigned int vector, bool set);
+void hv_para_set_sint_proxy(bool enable);
 u64 hv_para_get_synic_register(unsigned int reg);
 void hv_para_set_synic_register(unsigned int reg, u64 val);
 void hyperv_cleanup(void);