diff options
| author | Hou Wenlong <houwenlong.hwl@antgroup.com> | 2025-09-23 08:37:37 -0700 |
|---|---|---|
| committer | Sean Christopherson <seanjc@google.com> | 2025-09-23 08:55:20 -0700 |
| commit | 9bc366350734246301b090802fc71f9924daad39 (patch) | |
| tree | 9a786961efa1a2979a055ca2c9713c1752cd710f | |
| parent | 5b66e335ead6472f336b4d7d9cbf14488b844f27 (diff) | |
KVM: x86: Add helper to retrieve current value of user return MSR
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.
Cc: stable@vger.kernel.org
Signed-off-by: Hou Wenlong <houwenlong.hwl@antgroup.com>
[sean: drop "cache" from the name, make it a one-liner, tag for stable]
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Link: https://lore.kernel.org/r/20250923153738.1875174-2-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
| -rw-r--r-- | arch/x86/include/asm/kvm_host.h | 1 | ||||
| -rw-r--r-- | arch/x86/kvm/x86.c | 6 |
2 files changed, 7 insertions, 0 deletions
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 822a5596a4a0..0d6a4af79b78 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -2357,6 +2357,7 @@ 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(unsigned int slot); 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 1d7faf8bc785..5ac2183b9993 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -677,6 +677,12 @@ 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(unsigned int slot) +{ + return this_cpu_ptr(user_return_msrs)->values[slot].curr; +} +EXPORT_SYMBOL_GPL(kvm_get_user_return_msr); + static void drop_user_return_notifiers(void) { struct kvm_user_return_msrs *msrs = this_cpu_ptr(user_return_msrs); |