On 04-06-2025 06:13, Roman Kisel wrote:
The confidential VMBus is built on the guest talking to the
paravisor only.
Provide functions that allow manipulating the SynIC registers
via paravisor. No functional changes.
Signed-off-by: Roman Kisel <romank@xxxxxxxxxxxxxxxxxxx>
Reviewed-by: Alok Tiwari <alok.a.tiwari@xxxxxxxxxx>
---
arch/x86/kernel/cpu/mshyperv.c | 44 ++++++++++++++++++++++++++++++++++
drivers/hv/hv_common.c | 13 ++++++++++
include/asm-generic/mshyperv.h | 2 ++
3 files changed, 59 insertions(+)
diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index 3e2533954675..83a85d94bcb3 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -89,6 +89,50 @@ void hv_set_non_nested_msr(unsigned int reg, u64 value)
}
EXPORT_SYMBOL_GPL(hv_set_non_nested_msr);
+/*
+ * Attempt to get the SynIC register value from the paravisor.
+ *
+ * Not all paravisors support reading SynIC registers, so this function
+ * may fail. The register for the SynIC of the running CPU is accessed.
+ *
+ * Writes the SynIC register value into the memory pointed by val,
+ * and ~0ULL is on failure.
+ *
+ * Returns -ENODEV if the MSR is not a SynIC register, or another error
+ * code if getting the MSR fails (meaning the paravisor doesn't support
+ * relaying VMBus comminucations).
comminucations -> communications
+ */
+int hv_para_get_synic_register(unsigned int reg, u64 *val)
+{
+ u64 reg_val = ~0ULL;
+ int err = -ENODEV;
+
+ if (hv_is_synic_msr(reg))
+ reg_val = native_read_msr_safe(reg, &err);
+ *val = reg_val;
+
+ return err;
+}
+
+/*
+ * Attempt to set the SynIC register value with the paravisor.
+ *
+ * Not all paravisors support reading SynIC registers, so this function
+ * may fail. The register for the SynIC of the running CPU is accessed.
you are writing, not reading. ?
-> "Not all paravisors support writing SynIC registers"
+ *
+ * Sets the register to the value supplied.
+ *
+ * Returns: -ENODEV if the MSR is not a SynIC register, or another error
+ * code if writing to the MSR fails (meaning the paravisor doesn't support
+ * relaying VMBus comminucations).
+ */
+int hv_para_set_synic_register(unsigned int reg, u64 val)
+{
+ if (!hv_is_synic_msr(reg))
+ return -ENODEV;
+ return wrmsrl_safe(reg, val);
+}
Thanks,
Alok
