6.17-stable review patch. If anyone has any objections, please let me know.
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From: Hou Wenlong houwenlong.hwl@antgroup.com
commit 9bc366350734246301b090802fc71f9924daad39 upstream.
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/include/asm/kvm_host.h | 1 + arch/x86/kvm/x86.c | 6 ++++++ 2 files changed, 7 insertions(+)
--- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -2356,6 +2356,7 @@ 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) { --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -677,6 +677,12 @@ void kvm_user_return_msr_update_cache(un } 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);