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| author | Hou Wenlong <houwenlong.hwl@antgroup.com> | 2025-09-23 08:37:37 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-10-19 16:37:00 +0200 |
| commit | 1406a670b314f10eedece732ddbe57964b75334a (patch) | |
| tree | 8723dd15c60081db276632df1ec121412de7834b /arch | |
| parent | d4c322913af71d9cee6889dd8a22873b9fac004b (diff) | |
| download | linux-1406a670b314f10eedece732ddbe57964b75334a.tar.gz linux-1406a670b314f10eedece732ddbe57964b75334a.tar.bz2 linux-1406a670b314f10eedece732ddbe57964b75334a.zip | |
KVM: x86: Add helper to retrieve current value of user return MSR
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>
Diffstat (limited to 'arch')
| -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 f19a76d3ca0e..a35ee44ec70a 100644 --- 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) { diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index e6ae226704cb..fe893dcfdd79 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); |