In the user return MSR support, the cached value is always the hardware value of the specific MSR. Therefore, add a helper to retrieve the cached value, which can replace the need for RDMSR, for example, to allow SEV-ES guests to restore the correct host hardware value without using RDMSR. Signed-off-by: Hou Wenlong --- arch/x86/include/asm/kvm_host.h | 1 + arch/x86/kvm/x86.c | 8 ++++++++ 2 files changed, 9 insertions(+) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index cb86f3cca3e9..2cbb0f446a9b 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -2376,6 +2376,7 @@ int kvm_add_user_return_msr(u32 msr); int kvm_find_user_return_msr(u32 msr); int kvm_set_user_return_msr(unsigned index, u64 val, u64 mask); void kvm_user_return_msr_update_cache(unsigned int index, u64 val); +u64 kvm_get_user_return_msr_cache(unsigned int index); static inline bool kvm_is_supported_user_return_msr(u32 msr) { diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 6d85fbafc679..88d26c86c3b2 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -675,6 +675,14 @@ void kvm_user_return_msr_update_cache(unsigned int slot, u64 value) } EXPORT_SYMBOL_GPL(kvm_user_return_msr_update_cache); +u64 kvm_get_user_return_msr_cache(unsigned int slot) +{ + struct kvm_user_return_msrs *msrs = this_cpu_ptr(user_return_msrs); + + return msrs->values[slot].curr; +} +EXPORT_SYMBOL_GPL(kvm_get_user_return_msr_cache); + static void drop_user_return_notifiers(void) { struct kvm_user_return_msrs *msrs = this_cpu_ptr(user_return_msrs); base-commit: 603c090664d350b7fdaffbe8e6a6e43829938458 -- 2.31.1