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Message-Id: <20201119233257.2939-11-chang.seok.bae@intel.com>
Date: Thu, 19 Nov 2020 15:32:45 -0800
From: "Chang S. Bae" <chang.seok.bae@...el.com>
To: tglx@...utronix.de, mingo@...nel.org, bp@...e.de, luto@...nel.org,
x86@...nel.org
Cc: len.brown@...el.com, dave.hansen@...el.com, jing2.liu@...el.com,
ravi.v.shankar@...el.com, linux-kernel@...r.kernel.org,
chang.seok.bae@...el.com, kvm@...r.kernel.org
Subject: [PATCH v2 10/22] x86/fpu/xstate: Update xstate save function for supporting dynamic user xstate
copy_xregs_to_kernel() used to save all user states in an invariably
sufficient buffer. When the dynamic user state is enabled, it becomes
conditional which state to be saved.
fpu->state_mask can indicate which state components are reserved to be
saved in XSAVE buffer. Use it as XSAVE's instruction mask to select states.
KVM saves xstate in guest_fpu and user_fpu. With the change, the KVM code
needs to ensure a valid fpu->state_mask before XSAVE.
No functional change until the kernel supports dynamic user states.
Signed-off-by: Chang S. Bae <chang.seok.bae@...el.com>
Reviewed-by: Len Brown <len.brown@...el.com>
Cc: x86@...nel.org
Cc: linux-kernel@...r.kernel.org
Cc: kvm@...r.kernel.org
---
arch/x86/include/asm/fpu/internal.h | 3 +--
arch/x86/kernel/fpu/core.c | 2 +-
arch/x86/kvm/x86.c | 11 ++++++++---
3 files changed, 10 insertions(+), 6 deletions(-)
diff --git a/arch/x86/include/asm/fpu/internal.h b/arch/x86/include/asm/fpu/internal.h
index 3201468ff4aa..75196d10aa71 100644
--- a/arch/x86/include/asm/fpu/internal.h
+++ b/arch/x86/include/asm/fpu/internal.h
@@ -332,9 +332,8 @@ static inline void copy_kernel_to_xregs_booting(struct xregs_state *xstate)
/*
* Save processor xstate to xsave area.
*/
-static inline void copy_xregs_to_kernel(struct xregs_state *xstate)
+static inline void copy_xregs_to_kernel(struct xregs_state *xstate, u64 mask)
{
- u64 mask = xfeatures_mask_all;
u32 lmask = mask;
u32 hmask = mask >> 32;
int err;
diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
index dca4961fcc36..ece6428ba85b 100644
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -99,7 +99,7 @@ int copy_fpregs_to_fpstate(struct fpu *fpu)
if (likely(use_xsave())) {
struct xregs_state *xsave = &xstate->xsave;
- copy_xregs_to_kernel(xsave);
+ copy_xregs_to_kernel(xsave, fpu->state_mask);
/*
* AVX512 state is tracked here because its use is
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index abd5ff338155..023db770b55f 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -9212,15 +9212,20 @@ static int complete_emulated_mmio(struct kvm_vcpu *vcpu)
static void kvm_save_current_fpu(struct fpu *fpu)
{
+ struct fpu *src_fpu = ¤t->thread.fpu;
+
/*
* If the target FPU state is not resident in the CPU registers, just
* memcpy() from current, else save CPU state directly to the target.
*/
- if (test_thread_flag(TIF_NEED_FPU_LOAD))
- memcpy(&fpu->state, ¤t->thread.fpu.state,
+ if (test_thread_flag(TIF_NEED_FPU_LOAD)) {
+ memcpy(&fpu->state, &src_fpu->state,
fpu_kernel_xstate_default_size);
- else
+ } else {
+ if (fpu->state_mask != src_fpu->state_mask)
+ fpu->state_mask = src_fpu->state_mask;
copy_fpregs_to_fpstate(fpu);
+ }
}
/* Swap (qemu) user FPU context for the guest FPU context. */
--
2.17.1
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