From a156ad8c508209ce22f3213d25c3c2ae1774a57d Mon Sep 17 00:00:00 2001 From: Roman Kisel Date: Wed, 8 Oct 2025 16:34:07 -0700 Subject: [PATCH] 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 Reviewed-by: Alok Tiwari Reviewed-by: Tianyu Lan Reviewed-by: Michael Kelley Signed-off-by: Wei Liu --- arch/x86/kernel/cpu/mshyperv.c | 29 +++++++++++++++++++++++++---- drivers/hv/hv_common.c | 5 +++++ include/asm-generic/mshyperv.h | 1 + 3 files changed, 31 insertions(+), 4 deletions(-) diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c index eb9f1d7eec61b..80a641a6ac48b 100644 --- a/arch/x86/kernel/cpu/mshyperv.c +++ b/arch/x86/kernel/cpu/mshyperv.c @@ -28,6 +28,7 @@ #include #include #include +#include #include #include #include @@ -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 c39472ae8345a..4b44da7f23b27 100644 --- 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 c328265de6244..ecedab554c80d 100644 --- 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); -- 2.47.3