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Peter Anvin" , Eric Biggers , Stanislav Spassov Subject: [PATCH v5 4/7] x86/fpu: Initialize guest FPU permissions from guest defaults Date: Thu, 10 Apr 2025 15:24:44 +0800 Message-ID: <20250410072605.2358393-5-chao.gao@intel.com> X-Mailer: git-send-email 2.46.1 In-Reply-To: <20250410072605.2358393-1-chao.gao@intel.com> References: <20250410072605.2358393-1-chao.gao@intel.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Currently, fpu->guest_perm is copied from fpu->perm, which is derived from fpu_kernel_cfg.default_features. Guest defaults were introduced to differentiate the features and sizes of host and guest FPUs. Copying guest FPU permissions from the host will lead to inconsistencies between the guest default features and permissions. Initialize guest FPU permissions from guest defaults instead of host defaults. This ensures that any changes to guest default features are automatically reflected in guest permissions, which in turn guarantees that fpstate_realloc() allocates a correctly sized XSAVE buffer for guest FPUs. Suggested-by: Chang S. Bae Signed-off-by: Chao Gao --- arch/x86/kernel/fpu/core.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c index 25f13cc8ad92..e23e435b85c4 100644 --- a/arch/x86/kernel/fpu/core.c +++ b/arch/x86/kernel/fpu/core.c @@ -543,8 +543,10 @@ void fpstate_reset(struct fpu *fpu) fpu->perm.__state_perm = fpu_kernel_cfg.default_features; fpu->perm.__state_size = fpu_kernel_cfg.default_size; fpu->perm.__user_state_size = fpu_user_cfg.default_size; - /* Same defaults for guests */ - fpu->guest_perm = fpu->perm; + + fpu->guest_perm.__state_perm = guest_default_cfg.features; + fpu->guest_perm.__state_size = guest_default_cfg.size; + fpu->guest_perm.__user_state_size = guest_default_cfg.user_size; } static inline void fpu_inherit_perms(struct fpu *dst_fpu)