[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [PATCH v1] x86/nestedsvm: write back V_NMI and V_NMI_MASK on nested #VMEXIT
- To: chunjie.zhu@xxxxxxxxxx
- From: Jan Beulich <jbeulich@xxxxxxxx>
- Date: Thu, 15 Oct 2026 11:48:06 +0200
- Authentication-results: eu.smtp.expurgate.cloud; dkim=pass header.s=google header.d=suse.com header.i="@suse.com" header.h="Content-Transfer-Encoding:Content-Type:In-Reply-To:Autocrypt:From:Content-Language:References:Cc:To:Subject:User-Agent:MIME-Version:Date:Message-ID"
- Autocrypt: addr=jbeulich@xxxxxxxx; keydata= xsDiBFk3nEQRBADAEaSw6zC/EJkiwGPXbWtPxl2xCdSoeepS07jW8UgcHNurfHvUzogEq5xk hu507c3BarVjyWCJOylMNR98Yd8VqD9UfmX0Hb8/BrA+Hl6/DB/eqGptrf4BSRwcZQM32aZK 7Pj2XbGWIUrZrd70x1eAP9QE3P79Y2oLrsCgbZJfEwCgvz9JjGmQqQkRiTVzlZVCJYcyGGsD /0tbFCzD2h20ahe8rC1gbb3K3qk+LpBtvjBu1RY9drYk0NymiGbJWZgab6t1jM7sk2vuf0Py O9Hf9XBmK0uE9IgMaiCpc32XV9oASz6UJebwkX+zF2jG5I1BfnO9g7KlotcA/v5ClMjgo6Gl MDY4HxoSRu3i1cqqSDtVlt+AOVBJBACrZcnHAUSuCXBPy0jOlBhxPqRWv6ND4c9PH1xjQ3NP nxJuMBS8rnNg22uyfAgmBKNLpLgAGVRMZGaGoJObGf72s6TeIqKJo/LtggAS9qAUiuKVnygo 3wjfkS9A3DRO+SpU7JqWdsveeIQyeyEJ/8PTowmSQLakF+3fote9ybzd880fSmFuIEJldWxp Y2ggPGpiZXVsaWNoQHN1c2UuY29tPsJgBBMRAgAgBQJZN5xEAhsDBgsJCAcDAgQVAggDBBYC AwECHgECF4AACgkQoDSui/t3IH4J+wCfQ5jHdEjCRHj23O/5ttg9r9OIruwAn3103WUITZee e7Sbg12UgcQ5lv7SzsFNBFk3nEQQCACCuTjCjFOUdi5Nm244F+78kLghRcin/awv+IrTcIWF hUpSs1Y91iQQ7KItirz5uwCPlwejSJDQJLIS+QtJHaXDXeV6NI0Uef1hP20+y8qydDiVkv6l IreXjTb7DvksRgJNvCkWtYnlS3mYvQ9NzS9PhyALWbXnH6sIJd2O9lKS1Mrfq+y0IXCP10eS FFGg+Av3IQeFatkJAyju0PPthyTqxSI4lZYuJVPknzgaeuJv/2NccrPvmeDg6Coe7ZIeQ8Yj t0ARxu2xytAkkLCel1Lz1WLmwLstV30g80nkgZf/wr+/BXJW/oIvRlonUkxv+IbBM3dX2OV8 AmRv1ySWPTP7AAMFB/9PQK/VtlNUJvg8GXj9ootzrteGfVZVVT4XBJkfwBcpC/XcPzldjv+3 HYudvpdNK3lLujXeA5fLOH+Z/G9WBc5pFVSMocI71I8bT8lIAzreg0WvkWg5V2WZsUMlnDL9 mpwIGFhlbM3gfDMs7MPMu8YQRFVdUvtSpaAs8OFfGQ0ia3LGZcjA6Ik2+xcqscEJzNH+qh8V m5jjp28yZgaqTaRbg3M/+MTbMpicpZuqF4rnB0AQD12/3BNWDR6bmh+EkYSMcEIpQmBM51qM EKYTQGybRCjpnKHGOxG0rfFY1085mBDZCH5Kx0cl0HVJuQKC+dV2ZY5AqjcKwAxpE75MLFkr wkkEGBECAAkFAlk3nEQCGwwACgkQoDSui/t3IH7nnwCfcJWUDUFKdCsBH/E5d+0ZnMQi+G0A nAuWpQkjM1ASeQwSHEeAWPgskBQL
- Cc: andrew.cooper3@xxxxxxxxxx, roger@xxxxxxxxxxxxxx, jason.andryuk@xxxxxxx, teddy.astie@xxxxxxxxxx, xen-devel@xxxxxxxxxxxxxxxxxxxx
- Delivery-date: Thu, 15 Oct 2026 09:48:13 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 15.10.2026 09:45, chunjie.zhu@xxxxxxxxxx wrote:
> From: Chunjie Zhu <chunjie.zhu@xxxxxxxxxx>
>
> With V_NMI_ENABLE set, the processor clears V_NMI and sets V_NMI_MASK when
> it takes the virtual NMI, and writes both back to the VMCB on #VMEXIT
> (APM vol.2 15.21.10).
>
> nsvm_vmcb_prepare4vmexit() only propagated V_TPR, V_IRQ and (conditionally)
> V_GIF from the L2 shadow VMCB into vmcb12. V_NMI and V_NMI_MASK were never
> copied back, so L1 kept seeing whatever it had last written, regardless of
> what happened in L2.
>
> Copy both back when L1 has enabled vNMI for its guest.
>
> Signed-off-by: Chunjie Zhu <chunjie.zhu@xxxxxxxxxx>
Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
with ...
> --- a/xen/arch/x86/hvm/svm/nestedsvm.c
> +++ b/xen/arch/x86/hvm/svm/nestedsvm.c
> @@ -1027,12 +1027,18 @@ nsvm_vmcb_prepare4vmexit(struct vcpu *v, struct
> cpu_user_regs *regs)
> /*
> * Virtual Interrupts. #VMEXIT writes back V_TPR and V_IRQ (APM vol.2
> * 15.6); the remaining fields do not change. Copy vGIF back only if
> - * enabled in L1.
> + * enabled in L1. With vNMI enabled, #VMEXIT also writes back V_NMI and
> + * V_NMI_MASK (APM vol.2 15.21.10).
... the section title used here. As said recently in other contexts, if you
also want to name the section number, then that wants accompanying by the
doc revision (to disambiguate). Same for the patch description, obviously,
but in code comments that's yet more important.
Jan
|
