Hi Philippe, Thanks for your review comment! But if the patch is already queued, is it too late to apply it?
Kind regards, Zero Tang On Mon, Aug 18, 2025 at 8:16 PM Philippe Mathieu-Daudé <phi...@linaro.org> wrote: > Hi Zero, > > On 6/8/25 09:58, Zero Tang wrote: > > Replaces "long" with "int64_t" during canonicalization. > > > > --- > > In Linux GCC, "long" has 8 bytes. However, in msys2 GCC, "long" has 4 > > bytes. In this case, canonicalization would set all high bits to 1 when > > the segment base is bigger than 0x7FFF (assuming 48-bit linear > address). > > > > This is why QEMU-TCG in Windows cannot boot a bluepill-like hypervisor > > in UEFI, in that the guest IDT and GDT bases are above 0x7FFF, thereby > > resulting in incorrect bases. When an interrupt arrives, it would > > trigger a #PF exception; the #PF would trigger again, resulting in a > #DF > > exception; the #PF would trigger for the third time, resulting in > > triple-fault, and eventually causes the shutdown VM-Exit to the > > bluepill hypervisor right after it boots. > > > > In summary, this patch replaces "long" with "int64_t" in order to > enforce > > the canonicalization with 64-bit signed integers. > > > > Signed-off-by: Zero Tang <zero.tang...@gmail.com > > <mailto:zero.tang...@gmail.com>> > > --- > > target/i386/tcg/system/svm_helper.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/target/i386/tcg/system/svm_helper.c b/target/i386/tcg/ > > system/svm_helper.c > > index b27049b9ed..1ccfccf419 100644 > > --- a/target/i386/tcg/system/svm_helper.c > > +++ b/target/i386/tcg/system/svm_helper.c > > @@ -49,7 +49,7 @@ static void svm_save_seg(CPUX86State *env, int > > mmu_idx, hwaddr addr, > > static inline void svm_canonicalization(CPUX86State *env, > > target_ulong *seg_base) > > { > > uint16_t shift_amt = 64 - cpu_x86_virtual_addr_width(env); > > - *seg_base = ((((long) *seg_base) << shift_amt) >> shift_amt); > > + *seg_base = ((((int64_t) *seg_base) << shift_amt) >> shift_amt);\ > > Alternatively: > > *seg_base = sextract64(*seg_base, 0, 64 - > cpu_x86_virtual_addr_width(env)); > > > } > > > > static void svm_load_seg(CPUX86State *env, int mmu_idx, hwaddr addr, > > > > --- > > base-commit: e0006a86615baa70bc9d8b183e528aed91c1ac90 > > change-id: 20250806-fix-tcg-svm-canon-adbea9508073 > > > > Best regards, > > -- > > Zero Tang <zero.tang...@gmail.com <mailto:zero.tang...@gmail.com>> > >
