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Bae" To: pbonzini@redhat.com, seanjc@google.com Cc: kvm@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org, chang.seok.bae@intel.com Subject: [PATCH v5 10/20] KVM: x86: Support EGPR accessing and tracking for emulator Date: Mon, 20 Jul 2026 17:19:39 +0000 Message-ID: <20260720171949.498680-11-chang.seok.bae@intel.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260720171949.498680-1-chang.seok.bae@intel.com> References: <20260720171949.498680-1-chang.seok.bae@intel.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Extend the emulator context and GPR accessors to handle EGPRs before adding support for REX2-prefixed instructions. Like VCPU cache, the emulator can uniformly cache and track all GPRs. Also replace `1 << reg` with `BIT(reg)` in reg_read()/reg_write(). The former performs a signed 32-bit shift, which becomes undefined for R31. BIT() instead shifts an unsigned value that is suitable for all indices. Signed-off-by: Chang S. Bae --- V4 -> V5: Fix possible shift-out-of-bounds (review bot [*]) [*]: locally running Sashiko with gemini-3.1-pro-preview --- arch/x86/kvm/kvm_emulate.h | 20 +++++++++++--------- 1 file changed, 11 insertions(+), 9 deletions(-) diff --git a/arch/x86/kvm/kvm_emulate.h b/arch/x86/kvm/kvm_emulate.h index 3e375af15c03..b1498f618c81 100644 --- a/arch/x86/kvm/kvm_emulate.h +++ b/arch/x86/kvm/kvm_emulate.h @@ -109,13 +109,13 @@ struct x86_instruction_info { struct x86_emulate_ops { void (*vm_bugged)(struct x86_emulate_ctxt *ctxt); /* - * read_gpr: read a general purpose register (rax - r15) + * read_gpr: read a general purpose register (rax - r31) * * @reg: gpr number. */ ulong (*read_gpr)(struct x86_emulate_ctxt *ctxt, unsigned reg); /* - * write_gpr: write a general purpose register (rax - r15) + * write_gpr: write a general purpose register (rax - r31) * * @reg: gpr number. * @val: value to write. @@ -321,7 +321,9 @@ typedef void (*fastop_t)(struct fastop *); * also uses _eip, RIP cannot be a register operand nor can it be an operand in * a ModRM or SIB byte. */ -#ifdef CONFIG_X86_64 +#if defined(CONFIG_KVM_APX) +#define NR_EMULATOR_GPRS 32 +#elif defined(CONFIG_X86_64) #define NR_EMULATOR_GPRS 16 #else #define NR_EMULATOR_GPRS 8 @@ -381,9 +383,9 @@ struct x86_emulate_ctxt { u8 lock_prefix; u8 rep_prefix; /* bitmaps of registers in _regs[] that can be read */ - u16 regs_valid; + u32 regs_valid; /* bitmaps of registers in _regs[] that have been written */ - u16 regs_dirty; + u32 regs_dirty; /* modrm */ u8 modrm; u8 modrm_mod; @@ -547,8 +549,8 @@ static inline ulong reg_read(struct x86_emulate_ctxt *ctxt, unsigned nr) if (KVM_EMULATOR_BUG_ON(nr >= NR_EMULATOR_GPRS, ctxt)) nr &= NR_EMULATOR_GPRS - 1; - if (!(ctxt->regs_valid & (1 << nr))) { - ctxt->regs_valid |= 1 << nr; + if (!(ctxt->regs_valid & BIT(nr))) { + ctxt->regs_valid |= BIT(nr); ctxt->_regs[nr] = ctxt->ops->read_gpr(ctxt, nr); } return ctxt->_regs[nr]; @@ -562,8 +564,8 @@ static inline ulong *reg_write(struct x86_emulate_ctxt *ctxt, unsigned nr) BUILD_BUG_ON(sizeof(ctxt->regs_dirty) * BITS_PER_BYTE < NR_EMULATOR_GPRS); BUILD_BUG_ON(sizeof(ctxt->regs_valid) * BITS_PER_BYTE < NR_EMULATOR_GPRS); - ctxt->regs_valid |= 1 << nr; - ctxt->regs_dirty |= 1 << nr; + ctxt->regs_valid |= BIT(nr); + ctxt->regs_dirty |= BIT(nr); return &ctxt->_regs[nr]; } -- 2.53.0